Cooked meat must be included in supply (8)
I believe the answer is:
flambeed
'cooked' is the definition.
(flambeing is a type of cooking)
'meat must be included in supply' is the wordplay.
'meat' becomes 'lamb' (lamb is a kind of meat).
'must be included in' indicates putting letters inside.
'supply' becomes 'feed' (feeding is a kind of supplying).
'lamb' put within 'feed' is 'FLAMBEED'.
(Other definitions for flambeed that I've seen before include "cooked with brandy?" , "Lit up at dinnertime" .)