Fish with fingerprints (4)
I believe the answer is:
dabs
I believe this is a double definition.
'fish' is the first definition.
(I've seen this before)
'fingerprints' is the second definition.
(dab can mean a fingerprint)
'with' is the link.
(Other definitions for dabs that I've seen before include "'Pats at, with a cloth, say (4)'" , "digitally recorded evidence" , "Applies light touches" , "Informal adepts or kind of flat-fish" , "incriminating evidence, perhaps" .)