Vegetable casserole (11)
I believe the answer is:
ratatouille
'vegetable casserole' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for ratatouille that I've seen before include "Vegetable stew" , "Stewed vegetable dish" , "Film" , "vegetable casserole" , "cooked vegetables in a dish" .)