Clergyman, one accepting King's mistress as an exotic dish (10)
I believe the answer is:
cannelloni
'an exotic dish' is the definition.
'clergyman one accepting king's mistress' is the wordplay.
'clergyman' becomes 'canon' (canon is a kind of clergyman).
'one' becomes 'i' (Roman numeral).
'accepting' indicates putting letters inside.
'king's mistress' becomes 'nell'.
'canon'+'i'='canoni'
'canoni' enclosing 'nell' is 'CANNELLONI'.
'as' is the link.
(Other definitions for cannelloni that I've seen before include "course" , "Italian food" , "Stuffed pasta rolls" .)