Italian dish completely different to rosti (7)
I believe the answer is:
risotto
'italian dish' is the definition.
(type of Italian meal)
'completely different to rosti' is the wordplay.
'completely different' indicates an anagram.
'to'+'rosti'='torosti'
'torosti' anagrammed gives 'RISOTTO'.
(Other definitions for risotto that I've seen before include "Italian dish of rice, meat and vegetables" , "scoff" , "F" , "Main course" , "Savoury rice dish" .)