Thank you to Slormgorm. (This one has the same clue and solution hallmarks as those in the Independent set by Slormgorm’s other pseudonym.) Definitions are underlined in the clues.
Across
7. Bunch of liars in government tell tales (4)
SING : Hidden in(Bunch of) “liars in government”.
Answer: Act as an informer to the police/tell tales.
8. Desire to have union stirred up Paris, Idaho (10)
APHRODISIA : Anagram of(stirred up) PARIS, IDAHO.
Defn: .., sexually.
10. Nice for one retired to cuddle small men (6)
RESORT : RET(abbrev. for “retired”) containing(to cuddle) [ S(abbrev. for “small”) + OR(abbrev. for “other ranks”, men below commissioned officer level in the military).
Answer: An example of which/for one is Nice in southern France.
11. A tenor dwelling on run in off -Broadway theatre? (8)
ARTHOUSE: [ A + T(abbrev. for “tenor”, the voice) plus( … on) HOUSE(dwelling/a residence) ] containing( … in ) R(a. “run” in cricket scores).
I thought the wordplay was a bit convoluted.
12. A lot of fences take up too much of a wood (8)
MAHOGANY : MANY(a lot of/plenty) containing(fences) [ HOG(take up too much of something in an unfair way) + A ].
13. Party currently holding power could be locked up (6)
INSIDE : The [IN SIDE](what you might call the party/SIDE that is currently holding/IN power).
Defn: …/inside prison.
15. Naive ex-prince: “I need to change” (13)
INEXPERIENCED : Anagram of(… to change) EX-PRINCE: “I NEED.
18. Spiritual knowledge boring? “No!” sister reveals (6)
GNOSIS : Hidden in(… reveals) “boring? “No!” sister”.
20. Partnership coming from one-night stand, not date (8)
ALLIANCE : “dalliance”(casual sexual relationship/a one-night stand) minus(not) “d”(abbrev. for “date”).
22. Beer served by one’s husband makes you quite fat (8)
STOUTISH : STOUT(a strong dark beer) plus(served by) I(Roman numeral for “one”)’S + H(abbrev. for “husband”).
24. Religion is somewhat rubbish in total (6)
SHINTO : Hidden in(somewhat) “rubbish in total”.
Answer: A Japanese ….
25. Green site scrooge with flu developed (4,6)
GOLF COURSE : Anagram of(… developed) [SCROOGE plus(with) FLU ].
Defn: Where you will find a green/an area on which you putt.
26. Display behind flash old salesman’s back (4)
MOON : MO(short for “moment”/a very short period of time/a flash) + O(abbrev. for “old”) + last letter of(…’s back) “salesman”.
Defn: …/one’s backside.

Down
1. Freedom is, um… found in alcoholic drink (10)
LIBERATION : ER(like “um …”, an expression of hesitation) contained in(found in) LIBATION(in ancient Greece and Rome, an alcoholic drink offered to the gods).
2. Quality gag a turn getting Oscar prepared (1,4,3)
A GOOD ONE : A + GO(turn/one’s opportunity to do something that comes successively to each member in a group) plus(getting) O(letter represented by “Oscar” in the phonetic alphabet) + DONE(prepared/ready, as in “everything’s done for tonight’s dinner”).
Defn: …/a very funny joke.
3. Slogan that might grab you briefly? (6)
MANTRA : “mantrap”(something that might grab/catch you, in this case a trap for catching people, say, trespassers) minus its last letter(briefly).
4. Sorry Tory threesome making love to EU leaders (8)
CONTRITE : CON(abbrev. for a member of the Conservative Party/a Tory) + “trio”(a threesome/group of three, making love perhaps) replacing(making) “o”(letter representing 0/love in tennis scores) with 1st letters, respectively, of(… leaders) “to EU”.
5. Intolerant people can be bores outside of work (6)
BIGOTS : BITS(tools for boring/drilling holes) containing(outside of) GO(to function/work).
6. Ultimately, flatulists with gas affected behaviour (4)
AIRS: Last letter of(Ultimately) “flatulists” placed under(with?, in a down clue) AIR(the gas mixture we breathe in).
Defn: …/pretentious and artificial manner.
Not sure about the placement indicator for the “S”.
9. Ringer whose dirty pants might upset sprinter at the finish line? (5,8)
HEAVY BREATHER : Double defn: 1st: One who rings/calls on the phone and makes obscene/dirty heavy breathing/pants that might upset the one receiving the call; and 2nd: Cryptically, how you might describe a sprinter who has just completed a race/at the finish line.
14. One addict I sorted out shows devotion (10)
DEDICATION : Anagram of(… sorted) ONE ADDICT I.
16. God is on dope, according to a revisionist! (8)
POSEIDON : Anagram of(…, according to a revisionist) IS ON DOPE.
Answer: The ancient Greek god of the sea.
17. It is a march in which rioting occurs! (8)
CHARISMA : Anagram of(… in which rioting occurs) IS A MARCH.
Defn: …/attractiveness/appeal that someone has.
19. Jam on crustless rye is excessively dull (6)
STUFFY : STUFF(to jam/to fill tightly) plus(on, in a down clue) 1st and last letters deleted from(crustless) “rye”.
21. Leaving cover, exposed privates will get pounded (6)
LASHED : 1st letter deleted from(Leaving cover, in a down clue) “flashed”( what a flasher did/exposed his/her private parts/genitals in public).
Defn: …/beat forcefully against something, say, the sea against a cliff.
23. Third part of slogan found in Drink Coke! (4)
TOOT : 3rd letter of(Third part of) “slogan” contained in(found in) TOT(a small amount of a strong alcoholic drink).
Answer: In slang, a dose of cocaine/coke.
Too hard for me. Nho TOOT. Is CHARISMA really a synonym for It, which is more sex appeal than charisma?
Enjoyed the illustrated blog.
Thanks to Slormgorm and scchua.
ARTHOUSE
I read it as
A+T HOUSE on/by the side of R
and ‘in’ as a link word.
Enjoyable puzzle. Lovely blog.
Thanks Slomgorm and scchua.
KVa@2: I agree.
SM@1: As well as sex appeal Chambers has IT=”an indefinable crowning quality, personal magnetism”, which seems close enough to its definition of CHARISMA (“a personal quality or gift that enables an individual to impress and influence others”).
Thanks Hector@3
Is it just me or is there something a bit, er, untoward going on here? I mean, APHRODISIA, (D)ALLIANCE, (F)LASHED, MOON, HEAVY BREATHER, even “It” as in CHARISMA and maybe one or two others……… 🙂
vannucci @5: this setter always laces his puzzles with sex, drugs, and rock n roll. Some find it amusing, some find it a little much, and some find it amusing but still a little much. But either way, you know what to expect.
A steady work through the enjoyable smut, neither too much, nor unamusing… I don’t think I’ve been aware of TOOT, but it couldn’t have been much else. I was especially happy to see the insertions before the sunset, unusually for me…
Thanks Slormgorm n scchua
Tricky today so I did not finish, mainly because I had so many answers that I had worked out from their definition but that I could not parse, that I began to suspect I had some wrong ones. Usually when I get that feeling I have indeed made mistakes, though not today so I should perhaps have persevered.
I liked INEXPERIENCED. Not so keen on INSIDE. I don’t think anyone would use the expression “the in side” for the party holding power. It would have worked better if the allusion had been to a cricket team perhaps. I was also a bit dubious about air being defined as a gas when, as Scchua has pointed out, it is a mixture of gases.
I also am too innocent to have heard of TOOT!
We lost interest when we realised the direction the tone of some of the clues was taking, and didn’t bother to finish. But we thought the topical allusion in the surface of 15ac was brilliant!
Didn’t enjoy and my first major DNF for a while.
I loved this crossword, really inventive clueing which really needed outside the box thinking. I was close to giving up a few times but glad I persisted, once near the end you get one and all of a sudden the rest drop in, and the sense of achievement was worth it.
Some tremendous surfaces – 15a, 22a, 24a, 1d, 5d. 9d were my favourites
I failed in the southwest corner through no fault of my own, I maintain. For 22a I entered LARGEISH, which fits the definition and parses as (lager)* with ‘served’ as the anagrind + ISH. That kept me from getting 19d STUFFY and 23d TOOT, good clues both.
Others have noted Slormgorm’s fondness for sex, drugs and rock-and-roll. I missed out on those cornerstones of my generation’s youth. Sadly, mine was merely spent, so I now refer to it as my misspelt yoof.
(Autocorrect tried to change ‘yoof’ to ’Yoko’. How appropriate.)
Thanks, Slormgorm for the excellent puzzle, and scchua for the Ionic blog.