Pastry shell (5)
I believe the answer is:
crust
'pastry shell' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for crust that I've seen before include "Bit of toast, perhaps" , "Pie topping" , "Earth's outer layer" , "Hardened layer; pie top" , "Pie covering" .)