Casserole bit (3)
I believe the answer is:
pea
'casserole bit' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for pea that I've seen before include "Ape this plant badly" , "Climbing plant; vegetable" , "12 in a pod" , "Tiny stone" , "Cause of a princess's insomnia?" .)