Cereals so cooked in pot (9)
I believe the answer is:
casserole
'pot' is the definition.
(type of cooking pot)
'cereals so cooked' is the wordplay.
'cooked' indicates anagramming the letters (letters cooked into a new form).
'cereals'+'so'='cerealsso'
'cerealsso' anagrammed gives 'CASSEROLE'.
'in' is the link.
(Other definitions for casserole that I've seen before include "Stew; dish" , "Slow-cooked dish" , "Meat dish" , "Make a stew" , "Dish (served in a dish of the same name)" .)