Fish pie's crust coated with fish (3,5)
I believe the answer is:
sea perch
'fish' is the definition.
(I've seen this before)
'pie's crust coated with fish' is the wordplay.
'crust' suggests removing the centre (the outside or crust of the word is used).
'coated with' indicates putting letters inside.
'fish' becomes 'search' (I can't explain this - if you can you should believe this answer much more).
'pie' with its centre taken out is 'pe'.
'pe' going within 'search' is 'SEA-PERCH'.
Can you help me to learn more?
(Another definition for sea perch that I've seen is " type of fish".)