Nurse got cooked fish (8)
I believe the answer is:
sturgeon
'fish' is the definition.
(sturgeon is a kind of fish)
'nurse got cooked' is the wordplay.
'cooked' is an anagram indicator.
'nurse'+'got'='nursegot'
'nursegot' is an anagram of 'STURGEON'.
(Other definitions for sturgeon that I've seen before include "Large fish, valued for its roe" , "Our gents caught a large fish" , "provider of delicacy?" , "Source of caviar" , "Fish yielding caviar and isinglass" .)