Vocally it represents instrument (6)
I believe the answer is:
cymbal
'instrument' is the definition.
(I know that cymbal is a type of percussion instrument)
'vocally it represents' is the wordplay.
'vocally' shows a homophone (sound like).
'it represents' becomes 'symbol' (I've seen this before).
'symbol' sounds like 'CYMBAL'.
(Other definitions for cymbal that I've seen before include "Crashing instrument" , "One of a pair of percussion instruments" , "Disc of metal struck by a percussionist" , "Origin of the Clash" , "Percussionist's disc" .)