Scam at issue in part is famous fiddle (5)
I believe the answer is:
amati
'famous fiddle' is the definition.
(I've seen this in another clue)
'scam at issue in part' is the wordplay.
'in part' indicates the answer is hidden within the clue.
'AMATI' is hidden within 'scam at issue'.
'is' is the link.
(Other definitions for amati that I've seen before include "Renowned violin-making family" , "Old violin" , "One's played" , "Italian craftsmen" , "Violin or cello made by a Cremona family" .)