Dish offered by side finishing early (4)
I believe the answer is:
flan
'dish' is the definition.
(I've seen this before)
'side finishing early' is the wordplay.
'side' becomes 'flank' (I've seen this before).
'finishing early' means to remove the last letter.
'flank' with its final letter taken off is 'FLAN'.
'offered by' acts as a link.
(Other definitions for flan that I've seen before include "Open pastry dish" , "Open pastry filled with savouries, fruit or custard" , "Flat open tart" , "Baked dish filled with fruit or custard" , "dish, sweet or savoury" .)