Composer's part for violin (6)
I believe the answer is:
bridge
This clue is a double definition.
'composer's' is the first definition.
(I've seen this before)
'part for violin' is the second definition.
(I've seen this before)
(Other definitions for bridge that I've seen before include "Span, connecting structure" , "Game of cards" , "''Like a ... over troubled water'' (Simon and Garfunkel)" , "Connection crossing river etc" , "Span or connect" .)