Nurse got rotten fish (8)
I believe the answer is:
sturgeon
'fish' is the definition.
(type of fish)
'nurse got rotten' is the wordplay.
'rotten' indicates anagramming the letters.
'nurse'+'got'='nursegot'
'nursegot' with letters rearranged gives 'STURGEON'.
(Other definitions for sturgeon that I've seen before include "Fish - got nurse (anag)" , "Egg producer" , "Our gents caught a large fish" , "caviar suppliers" , "Fish valued for caviar" .)