Cook while stuffing baloney (5)
I believe the answer is:
roast
'cook' is the definition.
(roasting is a kind of cooking)
'while stuffing baloney' is the wordplay.
'while' becomes 'as'.
'stuffing' means one lot of letters goes inside another.
'baloney' becomes 'rot' (both can mean nonsense).
'as' inserted within 'rot' is 'ROAST'.
(Other definitions for roast that I've seen before include "Trash" , "Bake" , "Cook in oven or by exposure to heat" , "Oven-cook, tease" , "Cook, eg, joint of meat" .)