Cremona collectible (5)
I believe the answer is:
'cremona collectible' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for strad that I've seen before include "Valuable old violin" , "fiddle exposed" , "Valuable violin (abbrev.)" , "Old, very expensive violin (abbr)" , "that Grappelli could have played" .)