Cooks a potato dish (5)
I believe the answer is:
fries
'cooks' is the definition.
(frying is a kind of cooking)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for fries that I've seen before include "Cooks in fat" , "food for grazing?" , "Cooks; chips (Amer.)" .)