Fish and chips mostly cooked with lard (8)
I believe the answer is:
pilchard
'fish' is the definition.
(I know this)
'chips mostly cooked with lard' is the wordplay.
'mostly' means to remove the last letter.
'cooked with' indicates an anagram.
'chips' with its final letter removed is 'chip'.
'chip' anagrammed with 'lard' makes 'PILCHARD'.
'and' acts as a link.
(Other definitions for pilchard that I've seen before include "Small marine food fish" , "Small sea fish related to the herring" , "type of fish" , "Fish of herring family" , "'Small fatty fish, usually canned (8)'" .)