Contents of crisp fish croquette (7)
I believe the answer is:
rissole
'croquette' is the definition.
(I've seen this in another clue)
'contents of crisp fish' is the wordplay.
'contents of' means to look at the middle letters (the letters on the inside of the word).
'fish' becomes 'sole' (sole is a kind of fish).
The centre of 'crisp' is 'ris'.
'ris'+'sole'='RISSOLE'
(Other definitions for rissole that I've seen before include "Minced meat or fish deep fried in egg and breadcrumbs" , "Small pastry" , "Fried small cake of chopped meat" , "Sil rose for the meatball" , "Small cake of deep-fried minced meat" .)