It looks like we see The Ace of Hearts about once a year.
Preamble: One letter must be added to each clue to enable solving; in clue order these letters spell the first ten words of a quotation from a film (available on the IMDb website). The title of this film hints at how six cells must be treated in the final grid to resolve the problem that some clue answers are too long for the space available. Numbers in brackets after clues refer to the number of cells available. Ignoring the affected cells, all entries in the final grid are real words.
I don’t recall coming across the device of adding a letter to each clue before. I found this aspect of the puzzle quite tricky, not sure if it was the novelty or just because it was intrinsically so. FINESSER at 29a was obviously too long, as was CEBUS at 1d. Once I had a few answers that intersected these, it seemed that the overlong answers had either the end squeezed, FINESSER, or the beginning, CEBUS, leaving real words. (I discovered later that some were squeezed in the middle.) 
The extra letters weren’t helping either, since the list I’d been building was rather fragmented. I found a couple more overlong entries – SHILLINGS at 24a and VANTAGE at 31d, the latter leading to what would prove to be my first man: FINESSER VANTAGE. I nibbled away at the clues and finally had enough to google for the quotation: WE’LL BEGIN WITH A REIGN OF TERROR, A FEW MURDERS from the 1933 film The Invisible Man. Almost simultaneously the now rather obvious 1a PIECRUST came to me, bringing with it my second man: PIECRUST CEBUS, and the manner in which to resolve the clashes: make each man invisible.
HUSKINGS BANDONIONS soon followed, then the slightly different SHILLINGS LACE and INVASION CURSAL (a single letter squeezed &/or a squeezed middle). And finally BASHING NEEP gave me the sixth and final man to be rendered invisible.
Thanks go to The Ace of Hearts, some rather neat & inventive pairings, HUSKINGS BANDONIONS in particular stood out … though once I’d discovered the quotation and seen how to “resolve the problem”, finding the last three men felt a bit tiresome.
(If the Isle of Man sank then the island would no longer be visible.)
| No. | Clue | + | Answer | Wordplay |
| Across | ||||
| 1 | T[w]eak pictures covering pastry (6) | W | PIECRUST | [PICTURES]* |
| 6 | Old queen bees abruptly qui[e]t before festive gatherings (6) | E | HUSKINGS | KINGS (queen bees, obs) with HUS(h) (quiet) before |
| 10 | Roos were b[l]ack to chew sausage (9) | L | BOEREWORS | [ROOS WERE B(lack)]* |
| 12 | Ke[l]vin Scott’s friend stripped dark, tragic ruler (8, 2 words) | L | KING LEAR | K(elvin) INGLE (friend, Scott) (d)AR(k) |
| 13 | Is a member of [b]it in congress, its onset (6, 2 words) | B | SITS ON | (congres)S, ITS ON(set) |
| 14 | Battering trimmed b[e]acon in reserve (5) | E | BASHING | SHIN(e) (beacon) in BAG (reserve) |
| 15 | Lazy people initially should stop [g]ripping lout (5) | G | SLOBS | S(hould) S(top) around LB (lout) |
| 16 | Act[i]on Man? Note early English historian (7) | I | TOYNBEE | TOY (Action Man) NB (note) EE (early English) |
| 18 | Sire[n] protects the German/English actor (7) | N | HORDERN | HORN (siren) around DER (the, Ger) |
| 23 | Aged [w]Ally cuts metal device (7) | W | ISOTRON | SOT (fool, obs, wally) in IRON (device) |
| 24 | Co[i]ns, almost secluded, ailing at home, about to run out of gas (7) | I | SHILLINGS | SH(y) (secluded) ILL (ailing) IN (at home) GAS ¬ A(bout) |
| 26 | [T]Rue racecourse swindler getting young child (5) | T | LEGIT | LEG (racecourse swindler) IT (young child) |
| 27 | C[h]ampion in the Isle of Man parliament for distinguishing mark (5) | H | HAČEK | ACE (champion) in HK (House of Keys, Isle of Man parliament) |
| 29 | One pl[a]ying sophisticated accomplishments in Stratford ends sermon (6) | A | FINESSER | FINES (ends, L) SER(mon) |
| 32 | Spotted original cove[r], with half of us dead at end of world (8) | R | OCULATED | OC (original cover) U(s) LATE (dead) (worl)D |
| 33 | Unwinding unruly neologians h[e]aving answer (9) | E | LOOSENING | [NEOLOGIANS]* ¬ A(nswer) |
| 34 | Ra[i]d for instance stopping six others at the front entering hotel (6) | I | INVASION | AS (for instance) in VI (six) O(thers) in INN (hotel) |
| 35 | [G]Raze a marked area round the goal (6) | G | CREASE | double definition |
| Down | ||||
| 1 | Ca[n]ine has energy to transport monkeys (4) | N | CEBUS | C(anine) E(nergy) BUS (transport) |
| 2 | Captain’s relief company eg[o], in bed (7) | O | CO-PILOT | CO(mpany) I (ego) in PLOT (bed) |
| 3 | O[f] God as a ruler take in the end that examination! (8) | F | RECTORAL | REC (recipe, L, take) (tha)T ORAL (examination) |
| 4 | Dead bison s[t]ated you with short Indian grass (4) | T | URUS | U (you, homophone) RUS(a) (Indian grass) |
| 5 | Religious sit[e]s witnesses around Greek island (7) | E | SEKOSES | SEES (witnesses) around KOS (Greek island) |
| 6 | Heads following possibly st[r]op players of tango music (7) | R | BANDONIONS | ONIONS (heads) after STROP (band) |
| 7 | I li[r]e in sand mass surrounded by water (6) | R | ISLAND | I L(ire) in SAND |
| 8 | [O]Ban root vegetable lastly in Shropshire coffee shop (4) | O | NEEP | (i)N (Shropshir)E (coffe)E (sho)P |
| 9 | Police office[r] series accepted inside information on time (8) | R | SERGEANT | SER(ies) A(ccepted) in GEN (information) T(time) |
| 11 | Je[a]n in Germany sure to take seconds to enlisted men (4) | A | JANE | JA (sure, yes, Ger) (e)N(listed) (m)E(n) |
| 15 | American native almost [f]lashed during his old broadcast (8) | F | SHOSHONI | SHON(e) (flashed) in [HIS O(ld)]* |
| 17 | Perennial plant to exist around area of the Sahara, not[e] over Iowa (8) | E | BERGENIA | BE (exist) around ERG (area of the Sahara) N(ote) IA (Iowa) |
| 19 | Totally correct, [w]hat entitles Old Norse (7, 2 words) | W | RIGHT ON | RIGHT (what entitles) on (Old Norse) |
| 20 | Is older reworked [m]ore resistant to change? (7) | M | SOLIDER | [IS OLDER]* |
| 21 | Fleeces beside internal security included in the men[u]’s section (7) | U | TOISONS | TO (beside) IS (internal security) ON (included in the menu) S(ection) |
| 22 | Engraved wo[r]ks supplied by Daniel Lindstrom (6) | R | NIELLI | (Da)NIEL LI(ndstrom) |
| 25 | Bin[d] Latin expert (4) | D | LACE | L(atin) ACE (expert) |
| 28 | Perhaps ch[e]ats with nearly everybody about prehistoric earthwork (4) | E | CURSAL | CURS (cheats) AL(l) (everybody) |
| 30 | Zip name on fi[r]st (4) | R | NONE | N(ame) ONE (first) |
| 31 | Opportunity for Shakespeare to send moral to a [s]Tory on Spain (4) | S | VANTAGE | VAN (send) TAG (moral to a story) E (Spain) |
A tough workout, as adding letters is definitely harder than removing them. To give credit to AOH, they were all pretty fair and unambigous, perhaps with the exception of 7d where I had liNe not liRe initially.
As HG says, once the quote was done it still took a while to figure out all the remaining men, particularly as some of them were only using a single letter from one word, making the clashes harder to spot.
But a good fun puzzle, thank you!
I chalk this one up to experience. I solved most of the clues and identified the quote, but could never get my mind around what we were being asked to do with the key six cells, and I was positively hampered by having solved NEEP, introducing an erroneous P into 14A. As so often the instructions are pretty clear in retrospect, and it’s logical to pair the omitted letters in an Across/Down order, but it didn’t feel that way when looking at 34/28 or 14/8. My consolation is I think I might do better next time, so thanks to AoH and in particular to HolyGhost.
I got almost but not quite all the way there! I failed to consider that single letters already entered could share a cell with a fragment from a crossing word, so NEEP and LACE went in without me marking them as suspicious, though with hindsight I should have realised that the SLL string I had in 24a signalled something was up. I intended to come back to it before reading the solution but oops.
It was indeed a toughie so I don’t mind the setter pipping me at the post occasionally.
Many thanks to AoH and HG
I was stuck for a while on the idea that “We’ll start with arson” from the Shawshank Redemption was the first part of the quote – due to having “shaving answer” and therefore an S as the extra letter at 33 acc. Finally got to the Invisible Man quote after a rethink, and identified where five of the clashing cells were. I suspected that an invisible man (the “sinking island”) would emerge from the surplus letters in each of these cells, but I couldn’t see my way to solving certain key clues that might have helped identify them – CEBUS, HUSKINGS, FINESSER and CURSAL were too obscure for my rudimentary Googling abilities. And I wouldn’t have identified SHIP or HILL as “men”. Satisfying to finish most of the grid and find the film, but frustrating to fall short in the endgame, so only 5/10 this week. Thanks to HG for making the connections visible and to Expert/Champion of Hearts for the brain stretch.
Jon @4 I used the Chambers definitions of “man” to help identify the final couple of clashes – the list is relatively limited, so it was likely ship, hill etc were going to come up.
I always enjoy this genre, though it’s undeniably tricky with twelve answers of uncertain length. I also enjoyed the novel method of generating letters; I thought this was a very good puzzle. Like arnold@5, it was helpful to look up ‘man’ in Chambers, once the penny dropped (I had servant, vassal and half a husband). Thanks to AoH and HG.
Coming in late with little to add…. The adding-letters trick was new to me, and challenging. Good fun, and I was pleased to get there in the end, though my first clash in SHILLINGS/LACE made for an awkward start since HILL was perhaps the least obvious “man”. (As for others above, Chambers came to the rescue.) The top left corner held out for a long time because the monkey ending in B?S “surely had to be” COLOBUS. I blame Gerald Durrell.
Lots of thanks to The Ace of Hearts and HolyGhost.