Throw a bag and small instruments (9)
I believe the answer is:
castanets
'instruments' is the definition.
(castanet is a kind of instrument)
'throw a bag and small' is the wordplay.
'throw' becomes 'cast' (cast is a kind of throw).
'bag' becomes 'net' (I've seen this in other clues).
'and' is a charade indicator (letters next to each other).
'small' becomes 's' (abbreviation - e.g. clothes size).
'cast'+'a'+'net'+'s'='CASTANETS'
(Other definitions for castanets that I've seen before include "kitchen need?" , "Wooden percussion instrument" , "Flamenco clappers?" , "Clicking percussion instruments" .)