Russian ballerina is sweet (7)
I believe the answer is:
pavlova
I believe this clue is a double definition.
'russian ballerina' is the first definition.
(I've seen this in another clue)
'is sweet' is the second definition.
(I've seen this before)
(Other definitions for pavlova that I've seen before include "Meringue dessert" , "Meringue-based dessert" , "course" , "Sweet dish named after a ballerina" , "Sweet - dancer" .)