Paganini's instrument (6)
I believe the answer is:
violin
'paganini's instrument' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for violin that I've seen before include "Nigel Kennedy instrument" , "Bowed instrument" , "Instrument with four strings" , "Instrument with bow" , "An elevated fiddle" .)