Flake pastry with cheese crusts (5)
I believe the answer is:
piece
'flake' is the definition.
(thesaurus)
'pastry with cheese crusts' is the wordplay.
'pastry' becomes 'pie' (pie is a kind of pastry).
'with' means one lot of letters go next to another.
'crusts' suggests removing the centre (I've seen 'crust' mean this (the outside or crust of the word is used)).
'cheese' with its centre removed is 'ce'.
'pie'+'ce'='PIECE'
(Other definitions for piece that I've seen before include "Component; portion" , "artefact" , "bishop on board, say" , "Separate part of a whole" , "Musical composition" .)