5 'still' in the sense of silent, so think of another word for that (5 letters) around NT (National Trust) that will give you a group of musicians.
6 A 'social' is a party (the usual 2 letters) 'change in America' = American coins (5 letters) then check out the resulting word in Chambers, it's quite obscure.
8 '(to) Judge' is the def (to value?) a 5 letter word for 'gathers'/'gets together with' + E [all reversed].
9. When you see 'either' in a clue it usually means you've got OR in the middle of the answer, so 'either side of Kenya' is ?OR? (it's an African musical instrument).
13 'yellow is usually the tincture OR - 'atmosphere' is something like a halo - answer is a weather phenomenon.
15 It's a supporter of the Labour PM (Tony...) [8 letters, but minus the 1st and last letters] around ES (French) - and whenever there's 'most' in a clue it'll end ...iESt, then check out Chambers for the dialect word.