Roll filled with a fowl for the oven (7)
I believe the answer is:
roaster
'fowl for the oven' is the definition.
(I've seen this before)
'roll filled with a' is the wordplay.
'roll' becomes 'roster' ('roster' can be a synonym of 'roll').
'filled with' indicates putting letters inside.
'roster' enclosing 'a' is 'ROASTER'.
(Other definitions for roaster that I've seen before include "Chicken, perhaps" , "Fowl for the oven" , "A pig" , "hot day" , "Oven-ready bird" .)