Dessert with a crust (3)
I believe the answer is:
pie
'dessert with a crust' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for pie that I've seen before include "In the sky, it's an empty promise" , "Pastry product" , "Type of chart" , "Covered flan" , "Slapstick missile" .)