I am not sure how this is going to show up on the site – PeeDee’s tool was thwarted by a typo in the FT today (ACROSSs being the culprit) and therefore I have had to resort to manually typing everything up here. Kindly bear with the unjustified text if it so appears.
I cant say that this puzzle was smooth sailing – it required 3 individual attempts from, separated by a cup of coffee and a nice hot shower. 🙂 Some clues were not to my liking – especially 9,10ac which didnt have anything in the clue to indicate that the solution was to be looked up in the French lingo.
ACROSS
1. Inventor takes a long time touring the underworld (6)
[Solution]: EDISONÂ [Parsing] EON (long time) around DIS (Dis Pater, Roman god of the Underworld)
4. Well-defined muscle providing a bit of iron in special constable (8)
[Solution]: SPECIFIC [Parsing] PEC (muscle) IF (providing) I (bit of iron) in SC (special constable)
9,10. Fancy a conga’s uncouth? Each to his own? (6,1,3,4)
[Solution]: CHACUN A SON GOUT [Parsing] Anagram of A CONGA’S UNCOUTH, french for “Each to his own”.
12. Passed on (4)
[Solution]: OVER [Parsing]: Double/cryptic definition depending on how you look at the clue.
13. Break sadly over, canteen  beginning to empty out (10)
[Solution]: CONTRAVENE [Parsing]: Anagram of OVER CANTEeN less E (beginning of Empty)
15. Sort of socialist prayer to call on after current moves to the left (12)
[Solution]: COLLECTIVIST [Parsing] COLLECT (prayer) VISIT (call on) with an I (current) moved to the left
18. One who takes the p—- out of Scrooge? (5-7)
[Solution]: PENNY PINCHER [Parsing] P is short for Penny, Pincher is someone who steals / takes.
21. Vulnerable part of a French letter (primarily latex) found in China (10)
[Solution]: UNDERBELLY [Parsing] UN (French for ‘a’) ELL (The letter L, primarily Latex, the first character) in DERBY (Referring to Royal Crown Derby, the oldest company in UK making Bone China)
22. Tip number two (4)
[Solution]: DUMP [Parsing]: Double definition
24,25 Bald athlete surprisingly breaking your old record (6,2,3,3)
[Solution]: THAT’LL BE THE DAY [Parsing] Anagram of BALD ATHLETE and THY (Old English for ‘your’) – referring to the hit single by Buddy Holly and Jerry Allison.
26. Randy? Me, I get excited seeing those who deal in the white stuff (8)
[Solution]: DAIRYMEN [Parsing] Anagram of RANDY ME I
27. Quarter turn in the river (6)
[Solution]: FOURTH [Parsing]: U (type of turn) in FORTH (River Forth in England Scotland)
DOWN
1. Invade space right inside train (8)
[Solution]: ENCROACH [Parsing] EN (space, as in type of margin on pages) R (right) in COACH (train)
2,20. Actress from Basle cast in the first main part on New Year’s Day (8,6)
[Solution]: ISABELLE ADJANI [Parsing] Anagram of BASLE in I (first) LEAD (main part) on JANI (Jan 1st, New Year’s Day)
3. Chopin’s work in full (4)
[Solution]: OPUS [Parsing]: Cryptic definition, all of Chopin’s works were numbered Opus 1, Opus 2 and so on .. / in full could also be a reference to the complete form of op (work) in Chopin
5. Essential bit of magnetism provided by upbeat staff (8,4)
[Solution]: POSITIVE POLE [Parsing]: POSITIVE (upbeat) POLE (staff) – Reference to the North Pole of a Magnet
6. Going house to house in campaign involving chant in tents? (10)
[Solution]: CANVASSING [Parsing] CANVAS (tents) SING (chant) – I am not comfortable with how the clue reads as “chant in tents” instead of something to suggest that the “chant” comes after the “tents”.
7, 16. Painful condition that’s hard to bear (6,8)
[Solution]: FROZEN SHOULDER [Parsing]: FROZEN (hard) SHOULDER (bear)
8. Clipper sailing vessel (6)
[Solution]: CUTTER [Parsing]: Double definition
11. Altogether needing to solicit company (4,8)
[Solution]: TOUT ENSEMBLE [Parsing]: TOUT (solicit) ENSEMBLE (company)
14. Cold beer drunk to improve how the brain works? (10)
[Solution]: CEREBRALLY [Parsing] C (Cold) EREB (Anagram of BEER, drunk) RALLY (improve)
17. Effect of drug given credit, we hear, for work of art (8)
[Solution]: TRIPTYCH [Parsing]: TRIP (Effect of drug, referring to the high from narcotic usage) TYCH (homophone of tick, given credit)
19. Train departs as agreed (6)
[Solution]: SUITED [Parsing]: SUITE (train) D (departs)
23. Scary cry over some Pooh sticks (4)
[Solution]: SHOO [Parsing]: Hidden (in reverse, over) pOOH Sticks
27A Isn’t the River Forth in Scotland?
Thanks , Turbolegs, I needed your help for 1a. That sorted things went more smoothly.
We don’t usually spend so much time on a crossword; but this was so rich in enjoyment that we didn’t give up until we’d finished (sorry to be boring, but our house rules exclude electronic media.) Crazy syntax is Wanderer’s trademark, but you just have to get used to it. Thanks, Wanderer.
I think that 6D works as “chant in tents” means “sing under canvas”, using with under having its meaning in a down clue.
Hi Aid – Thanks for that. I cant make up my mind on whether that parsing for 6D is a bit contrived or just brilliant cluing. 🙂
Also Geoff told me that 9,10A makes an appearance in Colliers so may be I shouldnt be too harsh on the clue.
Ernie@1 – River Forth is indeed in Scotland. I will fix it now. Thanks for the help.
Thanks Grimalkin / Hornbeam for the comments.
Hi turbolgs, I’ve updated to blogging utility to be (even) more tolerant of spelling mistakes in the FT PDF file. Too late for this crossword but should work next time!