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 anagramming the letters (letters placed in a different order).
'parts' anagrammed gives '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" .)