Across:
8 Bass (B-) for group (-ORDER) (BORDER) with The Edge (BORDER),
9 Branch (OFFSHOOT) of old (O-) party (Fianna Fáil = -FF-) get the picture (-SHOOT) (OFFSHOOT),
10 Nocturnal flighty types (BATS) in combat ship (BATS in “combat ship”),
11 Fail to settle (NON-PAYMENT) in New York (NY = N-Y-) over broadcast (-ON-) by secretary (-PA-) to workers (-MEN-) with trade (-T) (NON-PAYMENT),
12 State (= homophone indicator) regime change (“coup” = “coo” = CO-O-) involves Frenchmen (Messieurs = -MM-) and new (-N) (COMMON) general (COMMON),
14 Retreat (HIDEAWAY) from pelt (HIDE-) found on a (-A-) thoroughfare (-WAY) (HIDEAWAY),
15 You’re doing this now (CROSSWORD PUZZLE) to take a stand against (CROSS-) upsetting (= reversal indicator) column (row = WOR-) by deputy head (‘deputy’ head = -D) at The Maze? (PUZZLE) (CROSSWORD PUZZLE),
18 Pupil leaves splinter group (‘pupil’ leaves ‘splinter group’ = sntergro = STRONGER) in better condition (STRONGER),
20 Sample of juice, baguette (sample of ‘juice, baguette’ = ICE BAG) and something for a headache (ICE BAG),
22 At one’s wits’ end (DISTRAUGHT) with drugs that (drugs that = D-STRAUGHT) unravel (= anagram indicator) around island (-I-) (DISTRAUGHT),
24 Credited with removing DIRT? (‘credited’ with removing ‘dirt’ = ceed = CEDE) I’ll give you that! (CEDE),
25 Guy (guy/male = HE-) Henry is central (‘Henry’ central = -N) to odd (= anagram indicator) thing (thing = NIGHT) (HEN NIGHT) that’s for women only (HEN NIGHT),
26 Renovators root out (‘renovators’ ‘root’ out/without “root” = envars = RAVENS) a number of birds (RAVENS).
Down:
1 A motto (a motto = TOMATO) rewritten (= anagram indicator) to gardener’s delight, for instance (type of TOMATO),
2 Counts (ADDS) half of those in 21 down (half of ‘add-ons’ = ADD-) at school (-S) (ADDS),
3 Not to mention (-AND) the last of the grain (the last of the ‘grain’ = -N-) in beer (beer = brew = BR- -EW) (BRAND NEW) that’s particularly fresh (BRAND NEW),
4 Combine (JOIN) with the extremes of Joseph Stalin (the extremes of ‘Joseph Stalin’ = JOIN),
5 Intimidated (AFRAID) by a (A-) loud (forte = -F-) break-in (-RAID) (AFRAID),
6 Great ape (CHIMPANZEE) of a famous revolutionary (CH-E) camouflages one (-I-) road (-M-) and most of the tank (most of the ‘panzer’ = -PANZE-) (CHIMPANZEE),
7 Ruin (DOWNFALL) in Ulster (DOWN-) has nothing to do with The Rising (-FALL) (DOWNFALL),
13 Most of (s) the address (“miss” without “s” = MIS-) by Lady Luck (-FORTUNE) (MISFORTUNE) in Hard Times perhaps (MISFORTUNE),
14 Pays for employing (HIRER) Shire horse with no shoes (‘Shire horse’ with no ‘shoes’ = orehr = HIRER),
16 Old family servant (RETAINER) is not the first (‘not’ the first = -N-) consumed by Eritrea (Eritrea = RETAI-ER) unrest (= anagram indicator) (RETAINER),
17 The decorators (PAINTERS) building (= anagram indicator) pantries (pantries = PAINTERS),
19 See out of sage-green (‘see’ out of ‘sage-green’ = agegrn = GRANGE) country house (GRANGE),
21 They’re the extra costs (ADD-ONS) of Breaking (= anagram indicator) Dad, son (dad + son = ADD-ONS),
23 Concealed by Greta Garbo (concealed by ‘Greta Garbo’ = etag) setting up (= reversal indicator) (etag = GATE) theatre (The GATE Theatre),
24 Sparkler (CAVA) unearthed in excavations (CAVA unearthed in ‘excavations’).