Got nurse cooking large fish (8)
I believe the answer is:
sturgeon
'large fish' is the definition.
(I've seen this before)
'got nurse cooking' is the wordplay.
'cooking' is an anagram indicator (cook can mean to falsify or distort).
'got'+'nurse'='gotnurse'
'gotnurse' anagrammed gives 'STURGEON'.
(Other definitions for sturgeon that I've seen before include "The fish for caviars" , "Large fish, valued for its roe" , "Fish - got nurse (anag)" , "caviar suppliers" , "Our gents, oddly, caught the fish" .)