Dish not often seen nibbled (7)
I believe the answer is:
rarebit
'dish' is the definition.
(rarebit is a kind of dish)
'not often seen nibbled' is the wordplay.
'not often seen' becomes 'rare'.
'nibbled' becomes 'bit' (I've seen this in other clues).
'rare'+'bit'='RAREBIT'
(Other definitions for rarebit that I've seen before include "Melted cheese on hot toast" , "Toasted cheese and bread" , "Cheese on toast - arbiter (anag)" , "Dish of grilled cheese on toast" , "Arbiter of traditional Welsh dish" .)