Cheese on toast, uncooked part (7)
I believe the answer is:
rarebit
'cheese on toast' is the definition.
(I've seen this before)
'uncooked part' is the wordplay.
'uncooked' becomes 'rare' (as in a rare steak).
'part' becomes 'bit' (both mean a piece of something).
'rare'+'bit'='RAREBIT'
(Other definitions for rarebit that I've seen before include "Melted cheese with ale on toast" , "on Welsh table?" , "Cheesy snack" , "cheesy meal" , "Arbiter of traditional Welsh dish" .)