Across:
8 A (-A-) new (-N-) bill (-AD-) in California (C-A) (CANADA) refers to state over the American border (CANADA),
9 Takes head off (s) those in 4 down (‘spar’ without ‘s’ = PAR-) and shreds (-SNIPS) (PARSNIPS) the vegetables (PARSNIPS),
10 Characters from across Cotswolds (characters from ‘acrosS COTswolds’ = SCOT) found living on Shetland (SCOT),
11 Club (-BAT-) in Corsica (Corsica) performs (= anagram indicator) (Corsica = ACRO-ICS) (ACROBATICS) a balancing act (ACROBATICS)
12 Finds fault with (BLAMES) blockhead (‘Block’ head = B-) weak (-LAME-) at school (-S) (BLAMES),
14 Uncultured (WILD-) magazine (-LIFE magazine) (WILDLIFE) for those with a gamey disposition perhaps (WILDLIFE),
15 Pick-up (HEAR-) Express (express = -SAY) for proof (EVIDENCE) (HEARSAY EVIDENCE) that one is not tolerated in court (HEARSAY EVIDENCE)
18 Those travelling the Sahara (CARAVANS) in moving vehicles (-VANS) following (= position indicator Irish friend (Irish ‘friend’ = CARA-) (CARAVANS),
20 Energetic (ACTIVE) part of the play, for example (Act IV = ACTIV-), linked to direction (direction East = -E) (ACTIVE),
22 Shortened (y) reddish brown (‘rusty’ without ‘y’ = RUST) water carrier (BUCKET) (RUST BUCKET) that’s dilapidated and found in the sea (RUST BUCKET),
24 Concealed by Greta Garbo (concealed by ‘grETA Garbo’ = etag) setting up (= reverse indicator) (etag = GATE) theatre (GATE Theatre),
25 Society (S-) gossips (-TALKERS) (STALKERS) – the one’s following other people (STALKERS),
26 Dale (VALLEY) speculatively ignored cup ties (‘speculatively’ ignored ‘cup ties’ = elavly = VALLEY).
Down:
1 Turns up (= reverse indicator), the foreign (the = le = -EL) credit (cr = -RC-) application (app) for the most part (‘app’ without ‘p’ = ap = PA-) (PARCEL) is in the post (PARCEL),
2 Flavour enhancer (SALT) found up (= reverse indicator) in Mount Lassen (found up in ‘mounT LASsen’ = tlas = SALT),
3 Graduate (MA = M-A) secures a (-A-) place (-LAY-) that is (is) up (= reverse indicator) (is = -SI-) (MALAYSIA) country (MALAYSIA),
4 Trade blows in Ring (SPAR in boxing ring) over (= reverse indicator) strikes (raps = SPAR),
5 Like some Customs’ (TRIBAL) people (tribe) losing European (e) (‘tribe’ without ‘e’ = TRIB-) area (-A-) at port (port/left = -L) (TRIBAL),
6 Chapter (INSTALMENT) from Mann’s title (Mann’s title) – Doctor…? (= anagram indicator) (Mann’s title = INSTALMENT),
7 Particular (SPECIFIC) epics (epics) adapted (= anagram indicator) (epics = SPECI-) by figurehead (‘Figure’ head = -F-) in charge (-IC) (SPECIFIC),
13 Commercial (MERCANTILE) car (MERC-) worker (-ANT-) loses the head (b) with ill temper (‘bile’ without ‘b’= -ILE) (MERCANTILE),
14 Daisy (daisy = WEED-) on bender (-S bend) (WEEDS), worn out by widow (widow’s WEEDS),
16 Force people to leave (EVACUATE) Takeaway (EVACUATE),
17 Popular (IN-) characters in 20 across (‘active’ = -ACTIVE) (INACTIVE) not working (INACTIVE),
19 The boy cleaned up in Boston (restaurant ‘busboy’ cleaned up in US = -BUSED) after (= position indicator) American (A-) (ABUSED) was assaulted (ABUSED),
21 Rejects (VETOES) a fair amount of (half of) the meat (veal) (half of ‘VEal’ = VE-) on the little piggies (-TOES) (VETOES),
23 A light touch (KISS) from banks kicking up a fuss (banks ‘KIcking up a fuSS’ = KISS),
24 It comes as a big blow perhaps (GALE) to air force? (air force = GALE).