Savoury dish, unusual, needs while (7)
I believe the answer is:
rarebit
'savoury dish' is the definition.
(I've seen this before)
'unusual needs while' is the wordplay.
'unusual' becomes 'rare' (rare can mean unusual or odd).
'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 "Arbiter of Welsh dish with melted cheese on toast" , "Cheesy snack" , "Dish of grilled cheese on toast" , "Welsh food?" , "on Welsh table?" .)