Across:
8 Turn one’s back on (INSULT) sunlit (sunlit = INSULT) complex (= anagram indicator),
9 Copper’s description (METALLIC) of climate (climate = META-LIC) change (= anagram indicator) around central Ireland (central “Ireland” = -L-) (METALLIC),
10 Nightspots (BEDS) for the kings and queens (BEDS),
11 Gives credit to those making up stories (AUTHORSHIP) in bookmakers (AUTHORS-) joint? (-HIP joint) (AUTHORSHIP),
12 Agreed to be taken out of ringside seat? (‘agreed’ to be taken out of ‘ringside seat ‘ = insist = INSIST) That’s it – I kid you not! (INSIST),
14 Makes an effort (ATTEMPTS) for first (A-) time (-T-) to seduce (-TEMPT-) head of state (head of ‘state’ = -S) (ATTEMPTS),
15 Player’s (players = ACTORS) backbone (CHARACTER) opened (= positional indicator) (CHARACTER ACTORS) by those in the theatre, not the main ones (CHARACTER ACTORS),
18 Expecting (PREGNANT) heads of public relations enterprise (heads of ‘public relations enterprise’ = PRE-) to fly (gnat = GNA-T) over Pole (North Pole = -N-) (PREGNANT),
20 The Examiner (the examiner = TESTER) is looking for evidence of a bad habit (TESTER looking for a bad habit/drugs)
22 A-list choir (a-list choir = HISTORICAL) medley (= anagram indicator) from a former era (HISTORICAL)
24 Fragment of Ecce Homo referenced (fragment of ‘Ecce Homo referenced’ = MORE) to boot (MORE),
25 Don’t forget (MEMORISE) viral phenomenon (MEM-E) about old (-O-) teacher (sir = -RIS-) retiring (= reversal indicator) (MEMORISE),
26 Lampoon (SATIRE) teacher (S-IR-) over a (-A-) primary text (primary ‘text’ = -T-) at the beginning of essay (at the beginning of ‘essay’ = -E) (SATIRE).
Down:
1 Concealed (UNSEEN) the identity of The Invisible Man (UNSEEN),
2 Those with familial connections (MUMS) to mushrooms on both sides of borders (‘mushrooms’ on both sides of borders = MUMS),
3 Unfinished (a) American city (‘Atlanta’ without ‘a’ = ATLANT-) opens in chaos (opens ‘in chaos’ = IC) (ATLANTIC) and it divides Europe and the New World (ATLANTIC),
4 Old magazine (Time = EMIT) reviews (= reversal indicator) issue (EMIT),
5 Went to restaurant (ATE OUT) tea (tea =ATE) dance (= anagram indicator) on holiday (OUT) (ATE OUT),
6 Finishes with 17 down (‘art class’ = CLASS-) and partner’s (partners = -MATES) (CLASSMATES) friends from school (CLASSMATES),
7 Address for man (MI-STER) hanging around Ulster (-NI-) (MINISTER) churchman (MINISTER),
13 System put in place to water down (IRRIGATION) European capital (capital of Latvia = -RIGA-) overwhelmed violently (= anagram indicator) in riot (in riot = IR-TION) (IRRIGATION),
14 Representative (AGENT) of a (A-) fairly (half of) hard-working type (half of ‘diligent’ = -GENT) (AGENT),
16 Hires one (hires one = HEROINES) playing (= anagram indicator) very brave women (HEROINES),
17 Rascals (rascals = AR- CLASS) admit starting trouble (starting ‘trouble’ = -T) (ART CLASS) where some are taught to be fast on the draw (ART CLASS),
19 Scared (AFRAID) of setting up (= reversal indicator) private account (diary) briefly (y) (‘diary’ without ‘y’ = diar = -RAID) for foreign footballers (FA = AF-) (AFRAID),
21 Mistakes (ERRORS) engineering (E-) on Rolls Royce (-RR-) is the gold (gold colour = -OR-) standard initially (‘standard’ initially = -S) (ERRORS),
23 Amir’s not involved in war crimes (‘amirs’ not involved in ‘war crimes’ = wrce = CREW) team (CREW),
24 Fragment of dogma technically (fragment of ‘dogma technically’ = MATE) derived from partner (MATE).