Urges not to cook fish (8)
I believe the answer is:
sturgeon
'fish' is the definition.
(type of fish)
'urges not to cook' is the wordplay.
'to cook' indicates anagramming the letters.
'urges'+'not'='urgesnot'
'urgesnot' anagrammed gives 'STURGEON'.
(Other definitions for sturgeon that I've seen before include "producer of caviar" , "Source of caviar" , "Our gents, oddly, caught the fish" , "So urgent to find caviare-bearing fish" , "producer of expensive eggs" .)