Violin relative (5)
I believe the answer is:
cello
'violin relative' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for cello that I've seen before include "Played by Rostropovich" , "music produced by this?" , "Tortelier's instrument" , "Jacqueline du Pre's instrument" , "Musical instrument like large violin held between knees" .)