Across:
8 Central to family (central to 'faMIly' = MI-) story (-LIE-) with unusual, extreme ('Unusual' extreme = -U) (MILIEU) background (MILIEU),
9 The Count is terrified he’ll see it (Count Dracula is terrified he’ll see DAYLIGHT) in The Sun presumably (DAYLIGHT),
10 There’s a lot of activity (HIVE of activity) in the queen’s residence (in the queen’s residence/bees’ home = HIVE),
11 Syrian miso (Syrian miso) soup (= anagram indicator) (Syrian miso = MISSIONARY) produced by faithful worker overseas perhaps (MISSIONARY)
12 Copper (Cu = C-U-) arrests that woman (-HER-) at back of nightclub (back of ‘nightcluB’ = -B) (CHERUB) with angelic figure (CHERUB)
14 Creative (ARTISTIC) type from museum (ART-) is (-IS-) getting endless (k) local credit (‘tick’ without ‘k’ = -TIC) (ARTISTIC),
15 9 across (‘daylight’ = DAYLIGHT) is taking offence (ROBBERY) (DAYLIGHT ROBBERY), as it’s some rip-off? (DAYLIGHT ROBBERY),
18 Dear me – it (dear me it) confused (= anagram indicator) (dear me it = DIAMETER) part of The Circle (DIAMETER),
20 Is it pushing it too much (TAXING) – private transport (TAXI-) is no good? (no good = -NG) (TAXING),
22 24-hours (DAY-) with fantasist (-DREAMER) (DAYDREAMER) out wool gathering when there’s still light? (‘woolgathering’ = DAYDREAMER),
24 Jokes (GAGS) in gatherings doing the rounds (in ‘GAtherinGS’ doing the rounds = GAGS),
25 Underground heating lighting up Old Nick’s (HELLFIRE) house warmer for one’s sins (= HELLFIRE),
26 Celebrated singer (diva) making a comeback (= reverse indicator) (diva = AVID-) touring Lombardy (touring ‘LombardY’ = -LY) (AVIDLY) with gusto (AVIDLY).
Down:
1 Representing Ulster (-NI-) in school (fish = FI-SH) (FINISH) cap (cap/conclude = FINISH),
2 Allude to (CITE) State’s (= homophone indicator) vision (‘sight’ = ‘CITE’),
3 New (= anagram indicator) Mum (mum = -UMM-) says (= homophone indicator) “bye” (bye) and takes a twist (= reverse indicator) (‘bye’ = ‘by’ = -Y B) in harbour boat (tug boat = T- -UG) (TUMMY BUG) – presumably that’s the Kathmandu quickstep? (TUMMY BUG),
4 Goes on to say (ADDS) Rocky is from dockyards (‘Rocky’ is from ‘dockyards’ = dads = ADDS),
5 Heartless (without centre/middle = ‘r’) in Endeavour (‘try’ without ‘r’ = TY-), the lead in Porridge (the lead in ‘Porridge’ = -P-) and the original (the ‘first’ = 1st = -IST) (TYPIST) key contributor to The Office (TYPIST),
6 View (WITNESS) fight (BOX) (WITNESS BOX) that’s synonymous with a lot of swearing, evidentially (WITNESS BOX),
7 Her intro (her intro) remarkably (= anagram indicator) (her intro = THORNIER) is causing the most distress (THORNIER),
13 They set an example (ROLE MODELS) for posers (MODELS) after (= positional indicator) getting a part in a film (ROLE) (ROLE MODELS),
14 Teacher (master) loses the head (m) (‘master’ without ‘m’ = ASTER) with one of Daisy’s family (ASTER),
16 Advertisement (AD = A-D) about soldier (-GI-) museum (-TATE- museum) (AGITATED) in a state (AGITATED),
17 Exposed (OUT-) by Shatter? (shatter = -BREAK) (OUTBREAK) That’s how wars begin! (OUTBREAK of war),
19 Shipmates ignore map (‘shipmates’ ignore ‘map’ = shites = THESIS) produced by scholar in final year (THESIS),
21 Minor annoyance (NIGGLE) for horse (-GG-) in river (NI-LE) (NIGGLE),
23 Rally (MEET) those on the periphery around (= reverse indicator) Texas Hold ’Em (those on the periphery around ‘TExas hold EM’ = MEET),
24 Brigades dismissed base (‘brigades’ dismissed ‘base’ = rigd = GRID) network (GRID).