Different parts of fish (5)
I believe the answer is:
sprat
'fish' is the definition.
(sprat is a kind of fish)
'different parts' is the wordplay.
'different' indicates an anagram.
'parts' is an anagram of 'SPRAT'.
'of' is the link.
(Other definitions for sprat that I've seen before include "Type of herring - small person or thing" , "It may catch a mackerel" , "one on a fat-free diet" , "Tiny fish" , "chap giving richer course material to the Dutch" .)