Most of tortoise cooked in dish (7)
I believe the answer is:
risotto
'dish' is the definition.
(risotto is a kind of dish)
'most of tortoise cooked' is the wordplay.
'most of' means to remove the last letter.
'cooked' is an anagram indicator (letters cooked into a new form).
'tortoise' with its final letter removed is 'tortois'.
'tortois' is an anagram of 'RISOTTO'.
'in' acts as a link.
(Other definitions for risotto that I've seen before include "It has roots in Italian rice-based dish" , "Italian course" , "Italian food" , "F" , "Rice/stock dish" .)