Savoury dish, lightly cooked, needs while (7)
I believe the answer is:
rarebit
'savoury dish' is the definition.
(I've seen this before)
'lightly cooked needs while' is the wordplay.
'lightly cooked' becomes 'rare' (I've seen this before).
'needs' is a charade indicator (letters next to each other).
'while' becomes 'bit' (both can mean an amount of time).
'rare'+'bit'='RAREBIT'
(Other definitions for rarebit that I've seen before include "Welsh snack" , "Melted cheese on hot toast" , "Melted cheese with ale on toast" , "Arbiter of traditional Welsh dish" , "Dish of grilled cheese on toast" .)