Breakfast dish that's served in prison (8)
I believe the answer is:
porridge
'breakfast dish' is the definition.
(I've seen this in another clue)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for porridge that I've seen before include "Oat dish; time in prison (slang)" , "Hot breakfast food" , "Eat for breakfast in prison" , "Spell in jail and breakfast food" , "Breakfast dish of boiled oatmeal" .)