Across:
8 Son gets out of limousine (‘son’ gets out of ‘limousine’ = limuie = MILIEU) in cultural surroundings (MILIEU),
9 Incidents (EPISODES) of nasty (= anagram indicator) spies (spies = EPIS-S) hiding most of (c) the code (‘code’ without ‘c’ = -ODE) (EPISODES),
10 Half of those in 9 across (half of ‘episodes’ = ODES) produced by linesman (ODES),
11 Criminal (= anagram indicator) sent heroin (sent heroin = RHINESTONE) with fake jewellery (RHINESTONE),
12 In part, impede man determined (in part, ‘impede man determined’ = DEMAND) to put in forceful request (DEMAND),
14 Sales rep (sales rep = RELAPSES) drunkenly (= anagram indicator) falls off the wagon (RELAPSES),
15 Holiday home (COTTAGE) in sturdy (in sturdy = INDUSTRY) complex (= anagram indicator) (COTTAGE INDUSTRY) selling homemade bread (COTTAGE INDUSTRY),
18 The Young Turks perhaps (OTTOMANS) could be footy types of props (footstools = OTTOMANS),
20 Local CIA (AGENCY) spy (agent) almost (t) (‘agent’ without ‘t’ = AGEN-) got caught (-C-) with unknown quantity of something (-Y) (AGENCY),
22 Is charged (-ION) for stamp (stamp/mark = IMPRESS-) from the start (= positional indicator) (IMPRESSION) or that’s the feeling (IMPRESSION),
24 Hook (LOOP) or Kitty (kitty/pool = LOOP) retiring? (= reversal indicator),
25 Similar to 23 down (FRAGMENT = similar to ‘iota’) in part (FRAGMENT),
26 Take dog from guardroom (take ‘dog’ from ‘guardroom’ = uarrom = ARMOUR) for knight’s protection (ARMOUR).
Down:
1 It’s difficult to figure out (RIDDLE) what this is? (this clue is a RIDDLE),
2 Give a wide berth to (MISS) what borders on mid-summer madness (what borders on ‘mid-summer madness’ = MISS),
3 Mouthy type in ring offers protection (mouth GUARD worn in boxing ring) to boxer (DOG) (GUARD DOG) working on a lead in the security business (GUARD DOG),
4 Food store specialist (DELI) in Dandelion Market (DELI in ‘Dandelion Market’),
5 Bar (LINE-) has a (-A-) heady libation (heady ‘libation’ = -L-) (LINEAL) that’s being handed down from one generation to the next (LINEAL),
6 Foams at the mouth (TOOTHPASTE) in corrupted (= anagram indicator) ETA hotspot (ETA hotspot = TOOTHPASTE),
7 Comet (Comet is one of Santa’s REINDEER) seen in the sky once a year? (REINDEER),
13 Pretend (ACT) you (YOU-) have a temper? (rage = -R AGE) (ACT YOUR AGE) Is that responsible advice from your mother! (ACT YOUR AGE),
14 Military actions (RAIDS) to remove ape from Paradise (remove ‘ape’ from ‘Paradise’ = radis = RAIDS),
16 Run rings around (OUTSMART) fool (OUTSMART),
17 Approach (DRAW NEAR) to reading (from the 3Rs = -R-) in morning breaks (morning breaks at dawn = D-AW N-) with a musician’s aptitude? (-EAR) (DRAW NEAR),
19 That isn’t a type of enquiry (ANSWER) that provides the solution (ANSWER),
21 Those providing the same line, time and again (CHORUS) or such (or such = CHORUS) trouble (= anagram indicator),
23 A bit (IOTA) of canal coming out of Catalonia (‘canal’ coming out of ‘Catalonia’ = taoi = IOTA),
24 University (University of Limerick = UL = LU-) brings back (= reversal indicator) politician (-MP) (LUMP) for some payment on retirement (LUMP sum).