Thanks Hoskins for an enjoyable one. Definitions are underlined in the clues.
Across
7. Rubbish people working away at Oxford? (8)
COBBLERS : Double defn: 1st: … in slang; and 2nd: Cryptically, those who are working on, such as resoling Oxfords, shoes that is.
Not working on, but in … 
9. Having sex without affection ultimately is sickening (6)
AILING : “nailing”(American slang for having sexual intercourse with) minus(without) last letter of(… ultimately) “affection“.
Defn: …/troubling/afflicting someone.
10. Conservative leader breaks soft strike deal (4)
PACT : 1st letter of(… leader) “Conservative” contained in(breaks) PAT(a soft strike/hit).
11. To mate with pint, getting drunk could be one (10)
TEMPTATION : Anagram of(… getting drunk) [ TO MATE plus(with) PINT].
Defn: That is. getting drunk ….
12. A kid with a chilled-out demeanour (2,4)
AT EASE : A + TEASE(to kid/to make fun of).
14. Succeed in marrying aristocrat, a man of property (8)
LANDLORD : LAND(to succeed in obtaining/getting, maybe a husband or wife) plus(marrying) LORD(an aristocrat/a noble).
15. Grab a nap, having necked last of beer (6)
ARREST : [A + REST(to take it easy, by having a nap, say)] containing(having necked/swallowed/drank) last letter of(last of) “beer“.
16. Big old gun member of the clergy picked up (6)
CANNON : Homophone of(… picked up) “canon”(a member of the clergy).
19. Spooner says Le Pétomane’s an object of historic interest (8)
ARTEFACT : Spoonerism(Spooner says) [“farty act”(entertainment by Le Pétomane, the French flatulist)].
21. Johnny Morris finally to meet PM in 1971 (6)
SHEATH : Last letter of(… finally) “Morris“plus(to meet) HEATH(Edward, UK Prime Minister in 1971).
Defn: A prophylactic/condom, or … in British slang.
23. When people must take on board one or some disparaging remarks (10)
ASPERSIONS : AS(when, as in “as you enter the room”) + PERSONS(people/beings) containing(must take on board) I(Roman numeral for “one”).
24. Prison in Texas first to execute crook? (4)
CANE : CAN(American, eg. Texan, slang for “prison”) + 1st letter of(first to) “execute“.
Defn: …/a shepherd’s hooked staff, a sort of cane.
25. Particle split by head of thermodynamics in city abroad (6)
BOSTON : BOSON(a sub-atomic particle) containing(split by) 1st letter of(head of) “thermodynamics“.
26. Chattering pirate’s first to be saved by navy chopper (8)
SPEAKING : 1st letter of(…’s first) “pirate” contained in(to be saved by) [SEA KING](an anti-submarine naval helicopter/chopper – originally American, with British and Canadian licensed versions).
Down
1. Old film star that Banksy might do in a toilet? (6)
BOGART : Cryptic defn: The stuff Banksy, the graffiti artist might do in a toilet/bog in British slang.
You must remember this …
“Play it, Sam”: 
… and again, “Play it, Sam”: 
… and not “Play it again, Sam”.
2. Topless dress? Rather! (1,3)
A BIT : “habit”(dress/loose long clothing worn by nuns and monks) minus its 1st letter(Topless …, in a down clue).
Defn: …/a fairly large amount, as a litotes.
3. Trousers round ankles possibly set bells off (8)
BELTLESS : Anagram of(… off) SET BELLS.
Defn: What you might be if your trousers end up round your ankles.
4. Continue to desire a licentious woman? (6)
WANTON : WANT(to desire/to long for) ON(to continue to/to carry on).
5. Flute Lance played could create noisy blasts? (10)
FLATULENCE : Anagram of(… played) FLUTE LANCE.
… cf 19 across
6. European article published about revolutionary Pole (8)
ANDORRAN : [AN(an article in grammar) + RAN(published, an article in a newspaper or magazine, say)] containing(about) reversal of(revolutionary) ROD(a pole/a thin straight bar).
8. Drop of sherry’s more than enough for a little taste (6)
SAMPLE : 1st letter of(Drop of) “sherry’s” + AMPLE(more than enough/more than sufficient).
13. Teenagers vandalised houses close to Muslim settlements (10)
AGREEMENTS : Anagram of(… vandalised) TEENAGERS containing(houses) last letter of(close to) “Muslim“.
Defn: … resolving conflicts or disputes.
15. Supporters one charged after a scrape (8)
ABRASION : [BRAS(short for “brassieres”/supporters of female breasts) + ION(an atom or molecule with an electric charge)] placed below(after, in a down clue) A.
17. One helping a relative to cross last section of bypass (8)
ASSISTER : A + SISTER(a relative viz. a female sibling) containing(to cross) last letter of(last section of) “bypass“.
18. Competitive games on the rise, leading to fits of bad temper (6)
STROPS : Reversal of(… on the rise, in a down clue) SPORTS(competitive games).
20. Toxic gas from behind engulfing almost all of pub (6)
ARSINE : ARSE(slang for “behind”/one’s buttocks) containing(engulfing) “inn”(a pub/a watering hole) mins its last letter(almost all of …).
22. I take digs from granny that’s offensive all round! (6)
TENANT : NAN(like “granny”, a familiar term for one’s grandmother) contained in(that’s/that has … all round) TET(the military offensive during the Vietnam War).
Defn: …/accommodation.
24. Drug that’s fine being taken in church (4)
COKE : OK(abbrev. for “Okay!”/that’s fine/good) contained in(being taken in) CE(abbrev. for the Church of England).
Defn: Slang for the drug, cocaine.
A quick solve for me but full of the usual Hoskins humour. I remember being amazed when I first heard about Le Pétomane’s act in my youth and somewhat later in life saw a film about it.
Favourites include: TEMPTATION and, of course, FLATULENCE. Thanks to Hoskins and scchua.
This was Hoskins at his most Hoskins-esque – you just go with the flow and smile at every reference to drugs, sex and toilet humour. He pulls it off with aplomb like no other setter can.
My only niggle was the use of an unindicated American term in 9a.
My podium choice is ARTEFACT, BOGART and ARSINE.
Many thanks to Hoskins and to scchua.
Much enjoyed, though some may take offence! And despite being a DNF as stupidly I couldn’t see ‘a bit’ at 2D, having assumed that the exclamation mark indicated that this was a reference to (e.g) Charles Hawtrey’s delivery of the word meaning ‘very much’. Thanks Hoskins and Sschua.
This was definitely Harry back to his old self and very nice to see. As RD said, he can pull it off in a way that few, if any, other setters are able to do.
Added one new piece of knowledge to my ‘Hoskins bank’ today, first time I’ve encountered the word for ‘having sex’ in 9a.
Top three for me were ARTEFACT, SHEATH & BOGART.
Many thanks, Hoskins, and thanks to scchua for the review.
Similar thoughts to Tatrasman here; about half a dozen needing cheats or just plain unsolved, though I don’t feel hard done by any of them (however I’ve only just got in the habit of thinking of “can” as toilet, never mind prison – 24a).
Many schoolboy sniggers here, with ARTEFACT and SHEATH being particular faves.
Bravo Hoskins and Scchua (especially for apt photos).
Thanks Hoskins and scchua
I think the clue for 26 is more subtle than you imply, scchua.
As well as being anti-submarine, Sea Kings were used extensively for air-sea rescue, making the use of ‘saved’ in the clue even more apposite.
Vintage Hoskins, immaculate and wicked. Loved it. Many excellent clues, Arsine and beltless among my favourites. And Bogart.
As others have commented already – vintage Hoskins which we loved.
BOGART raised a smile and a laugh. When we solved SHEATH and ARTEFACT there was no denying that it was Hoskins on top form.
Well done Hoskins and thanks to Scchua.
Got 7a and realised we were in for fun. Abashed to find myself on the wavelength, and on a Sunday,too.(It is Sunday, isn’t it? Lockdown makes it so hard to know). Failed on 6d, being fixated on “European article” being one indicator. Tut.
Thanks to scchua and Hoskins
Is the “without” in 9a to be read as “with/out”?
Went if fairly smoothly. Gave me quite a few laughs along the way.
Amusingly, I’d just been watching an episode of the TV show Warehouse 13 which is always talking about artefacts (or artifacts, in American) so 19ac came quickly.
Is “nailing” particularly American? Chambers doesn’t mark it as such. I’ve certainly heard the term.
Incidentally, 1dn reminds me of a clue that I think appeared in The Times must be at least thirty years ago:
Humphrey’s picturesque graffiti (6)
I didn’t regularly do The Times but this clue was considered near the knuckle that it got commented upon in other papers. What was The Times coming to, they asked. Especially as another clue in that puzzle was
Duchy suits women-libbers to a T (7)