Unusual coin found in dish (7)
I believe the answer is:
rarebit
'dish' is the definition.
(rarebit is a kind of dish)
'unusual coin' is the wordplay.
'unusual' becomes 'rare' (I've seen this before).
'coin' becomes 'bit' (I've seen this before).
'rare'+'bit'='RAREBIT'
'found in' acts as a link.
(Other definitions for rarebit that I've seen before include "Cheese/toast savoury" , "Cheese on toast - arbiter (anag)" , "mouthful?" , "Simple dish" , "on Welsh table?" .)