Fish held by Oscar Peterson (4)
I believe the answer is:
carp
'fish' is the definition.
(I know that carp is a type of fish)
'held by oscar peterson' is the wordplay.
'held by' indicates the answer is hidden within the clue.
'CARP' can be found hidden inside 'oscar peterson'.
(Other definitions for carp that I've seen before include "Fish; nag pettily" , "Swimmer" , "Complain like goldfish" , "Fish; find fault continually" , "Complain in manner of goldfish" .)