Thanks to Hoskins for his trademark cluing. Definitions are underlined in the clues.
Across
6. Happy prisoner with outdoor accommodation (7)
CONTENT : CON(short for “convict”/prisoner) plus(with) TENT(outdoor and portable accommodation/shelter).
7. Old joke about bit of zombifying gas (5)
OZONE : [O(abbrev. for “old”) + ONE(a joke, as in “have you heard the one about …?”)] containing(about) 1st letter of(bit of) “zombifying“.
9. Nag Republican to wear headgear (4)
CARP : R(abbrev. for “Republican”, a member of the Republican Party) contained in(to wear) CAP(form of headgear).
10. Naughty promises in burlesque? (10)
IMPRESSION : Anagram of(Naughty) PROMISES IN.
Defn: …/an absurd or comical imitation of something.
11. Man with hens, possibly in Scottish region? (8)
HEBRIDES : HE(third-party pronoun for a man) plus(with) BRIDES(possibly/could be, “hens”/women who are about to get married and are attending a female-only celebration/hen night).
13. Sexy books found in Morecambe? (6)
EROTIC : OT(abbrev. for the Old Testament, set of books in the Bible – including tales of rape, seduction, concubines and harlots, ie. with quite a bit of sex) contained in(found in) ERIC(Morecambe, one half of the comic duo, Morecambe and Wise).
15. Water pipe knight installed in toilet (4)
BONG : N(abbrev. for “knight”, in chess notation) contained in(installed in) BOG(slang for a toilet).
… for smoking cannabis and other drugs.
17. A charge or payment? (5)
AWARD : A + WARD(a charge/a child or young person under the care and control of a guardian).
Defn: … as awarded by a court of law for damages, say.
18. Swimmer, after split, ahead on the turn! (4)
TUNA : Anagram of(… on the turn) [A + NUT(slang for a person’s head)](“ahead” after split).
19. Become religious after knocking over veggie (6)
TURNIP : TURN(become/change into something else) + reversal of(… after knocking over) PI(short for “pious”/religious).
20. High-flyer with ego we all knocked about (5,3)
EAGLE OWL : Anagram of(with … knocked about) EGO WE ALL.

23. Hiker‘s nothing much to write home about (10)
PEDESTRIAN : Double defn: 2nd: …/uninspiring.
26. Smell repelled old European, one with wind (4)
OBOE : Reversal of(… repelled) BO(abbrev. for “body odour”, which itself is repellent) + O(abbrev. for “old”) + E(abbrev. for “European”).
Defn: …/one of the musicians in the wind section of an orchestra, playing this instrument by creating a rush of air/wind.
27. Slice of Urda wrapped in red fish (5)
TROUT : 1st letter of(Slice of) “Urda” contained in(wrapped in) TROT(short for “Trotskyist”, a follower of Trotsky, a communist/red with extreme left-wing views).
28. A support that’s held in extremely rebellious busts (7)
ARRESTS : A + [REST(a support, such as that used for a billiards cue) contained in(that’s held in) 1st and last letters of(extremely) “rebellious“].
Defn: … by the police, perhaps after a drug bust.
Down
1. Son horsing about with grandpa makes bloomer (10)
SNAPDRAGON : Anagram of(… horsing about …) [SON plus(with) GRANDPA].

2. In the sack, husband hot for booty (6)
BEHIND : BED(the sack/one’s sleeping place, as in “to hit the sack after a long day”) containing(In the …) [H(abbrev. for “husband”) + IN(popular/fashionable/hot)].
Defn: … which is slang for someone’s bottom/rear .
… an artistic booty.
3. On a drug, coming up (4)
ATOP : A + reversal of(…, coming up, in a down clue) POT(slang for the drug cannabis).
Defn: …/on top of.
4. Junkie right to punch church leader (8)
COKEHEAD : OK(okay/agreed!/all right!) contained in(to punch) [CE(abbrev. for the Church of England) + HEAD(the leader of a group or organisation)].
5. To me, the Indy crossword editor is a stud (4)
BOSS : Double defn. 1st: To me (the setter using the self-referential pronoun), this is what the Indy crossword editor is; and 2nd: … on the centre of a shield.
I presume Hoskins is not flattering his boss!
6. Centenarian leader and topless coquette don’t do it any more! (5)
CEASE : 1st letter of(… leader) “Centenarian” plus(and) “tease”(an example of which is a coquette/a female flirt) minus its 1st letter(topless …, in a down clue).
Defn: …/Stop!
Answer: As in “… and desist”.
8. Chart-topping book written about love, perhaps (7)
EMOTION : Reversal of(… written about) [NO.I(Number one/chart-topping, with the abbrev. and Roman numeral substitution) + TOME(a heavy, scholarly book)].
12. Censure son getting in after the agreed time (5)
SLATE : S(abbrev. for “son”) + LATE(getting in after the agreed time/unpunctual).
14. Where one might find a satellite dish for free? (2,3,5)
ON THE HOUSE : Double defn: 1st: …, literally.
… no cable.
16. For the most part, work fast to get rich (7)
OPULENT : 1st 3 letters of(For the most part) “opus”(a musical or literary work) + LENT(fast practised by Christians in the period preceding Easter/Lent).
17. Secretary going around with little desire for sex? (8)
APPETITE : Reversal of(… going around) PA(abbrev. for “personal assistant”/secretary) plus(with) PETITE(attractively small/little).
Defn: A desire for something, perhaps/?, sex.
21. Dope shot in group of quite high people (6)
GENTRY : GEN(dope/information) + TRY(a shot/an attempt at).
22. Clubs which are somewhat smaller than Forest? (5)
WOODS : Groups of trees and other vegetation that are each smaller than a forest.
Defn: … that are part of a golfer’s set.
24. School nurse taking temperature close to lido (4)
ETON : EN(abbrev. for “enrolled nurse”/a nurse in the UK) containing(taking) [T(symbol for “temperature” in physics) + last letter of(close to) “lido“].
Defn: Public … for boys in England.
25. Is Hoskins upset by male religious leader? (4)
IMAM : Reversal of(… upset) [AM I?](Is Hoskin?, with the setter using the self-referential pronoun) plus(by) M(abbrev. for “male”).
Defn: A Muslim …
Always love a Harry. Found cokehead / Award took a long time to solve and pedestrian although obvious I was less than convinced by.
Always doing the cheeky chappy, ooh err missus.
Typical Hoskins! Laughs and smiles all the way. BOSS was my favourite.
Many thanks to Hoskins for the fun and to scchua for the review.
Ooh, you are awful, but I like you, Hoskins. Plenty of hints at a misspent childhood … continuing into the present day if we go by the setter’s interventions elsewhere on this site. Plenty to enjoy with CEASE, ATOP, BOOTY and TURNIP my favourites.
Re HEBRIDES, I didn’t take ‘hen’ in the sense of hen nights but as a reference to the Scots term for woman which ties into both the surface and solution. A tiny ‘meh’: I know I’ve seen it used before but I’m not a huge fan of ‘slice of’ to indicate a single/first letter of a word (slice of Urda) even though it goes with the surface – though not, I imagine, with trout.
Thanks Hoskins and scchua
Excellent stuff as usual from Hoskins. Minor fish theme with CARP, TUNA, TROUT and, er, BONG…A(ward), a type of shad – coincidence perhaps? Thanks Hoskins and Sschua.
Fun as ever and thanks to both
No wonder I couldn’t get ‘dopehead’ to parse! All the usual fun of the fair from Harry and my top two were TURNIP & AWARD.
Thanks to Hoskins for the entertainment and to sschua for the review – and the pic of a lovely Eagle Owl. I’ve held one on my arm and it felt as light as a feather, though it looked rather fierce!
Great fun. I shall blame my own misspent youth, middle age and dotage for how long it took for the penny to drop on what were clever but very clear clues. Great pictures scchua
Many thanks to scchua for the usual amusingly pictured blog (is that a Kim Kardashian sculpture?!) and to all who commented and solved.
Great to see The Flash again after such a long time away – hope you, the missus and the dog are doing good and have avoided the worst of the damnable Covid, mate.
Glad this puzzle was enjoyed and I’ll be Arnie on the 15th of this month wiv another puzzle so see ya then.
Cheers and chin chin to all. 🙂
@Harry we’re all fine thanks, all jabbed up and not seen covid symptoms either. The pup is happy summer, beach and pub treats are back.
@Flash – excellent stuff. We shall have to have a beer sometime when I’m fully jabbed (and I can finally give you back that book you lent me!).