Across:
8 Cultured (POLITE) bar (POL-E) possesses it (-IT-) (POLITE),
9 Where you might find some message in a bottle (WASHED-UP on a beach) over the hill (WASHED-UP),
10 Some costal kibbutz (some ‘costal kibbutz’ = TALK) gossip (TALK),
11 One petitions (SUPPLICANT) to paint, sculp (paint sculp = SUPPLICANT), design (= anagram indicator) (SUPPLICANT),
12 The nerve of local (‘the nerve’ locally = ‘the BOTTLE’) bank (BOTTLE bank),
14 Relative (son = S-ON-) goes around yard (-Y-) with a measure of speed (-MPH-) and is first? Yes, (first ‘yes’ = -Y) (SYMPHONY) and Vaughan Williams’s second, for example (Vaughan Williams’s second SYMPHONY, for example),
15 Sweet (CHOCOLATE MOUSSE) type of dark brown (CHOCOLATE brown) rodent (MOU-SE) going around bend (U bend = - U-) (CHOCOLATE MOUSSE),
18 Head of state (GOVERNOR) from Oregon (Oregon = GO-ERNO-) troubled over sign (Victory sign = -V- sign) from Russian leader (‘Russian’ leader = -R) (GOVERNOR),
20 Didn’t ignore (HEEDED) that man (HE-) with two editors (ed + ed = -EDED) (HEEDED),
22 Network from web (TWITTER-) in (-IN-) Government (-G) (TWITTERING) is having an influence on social media (TWITTERING),
24 Young man (LAD-) to finally marry (finally ‘marry’ = -Y) (LADY) duke’s daughter (LADY),
25 Old (O-) female relative (niece = N- -IECE) holds record (EP = -E P-) (ONE-PIECE) in bathing suit (ONE-PIECE),
26 Just out (NEWEST) on the outskirts of New York forest (outskirts of “New York forest” = NEWEST).
Down:
1 Concealed peeping Tom atoning (concealed ‘peeping-Tom atoning’ = TOMATO) for this in the greenhouse (TOMATO),
2 Parasite (TICK) and angel fish removed from fishing tackle (‘angel fish’ removed from ‘fishing tackle’ = itck = TICK),
3 Possibly found outside 6 down (SEASHELL possibly found outside ‘beach house’) by a hard case on the coastline (SEASHELL),
4 Rightly taken from playwrights (‘rightly’ taken from ‘playwrights’ = paws = SWAP) in Exchange (exchange = SWAP),
5 Unanimously dismisses union (‘unanimously’ dismisses/ drops ‘union’ = amusly = ASYLUM) for those seeking shelter (ASYLUM),
6 Every one (-EACH) taking short hop (short ‘hop’ = HO-) in bus (B- -US-) to The Point (compass point east = -E) (BEACH HOUSE) should have room to see the sea from here (BEACH HOUSE),
7 British (B-) misrepresenting (= anagram indicator) nursing (nursing = -URNINGS) (BURNINGS) leads to firings (BURNINGS),
13 One of those local hearty types (TICKER) from band (TAPE) (TICKER TAPE) providing material for the parade (TICKER TAPE),
14 Stray (stray = SATYR) irritated (= anagram indicator) by butterfly (SATYR),
16 Double-cross (HOODWINK) local criminal (HOOD-) on a flutter (-WINK) (HOODWINK),
17 Navajo accommodation (Navajo hut = -HOGAN-) in May (MA-Y) (MAHOGANY) in the wood (MAHOGANY),
19 Selection drops lot (‘selection’ drops ‘lot’ = seecin = NIECES) of family members (NIECES),
21 First person (ELDEST) from Leeds (Leeds = ELDES-) playing (= anagram indicator) the lead (‘the’ lead = -T) (ELDEST),
23 It’s on the agenda (ITEM) to take the peas out of meat pies (take the ‘peas’ out of ‘meat pies’= meti = ITEM),
24 The foreign (the = LA-) women (-W-) with no (no) capital (n) (‘no’ capital/first letter = -N) (LAWN) requiring seed money perhaps to get started (LAWN).