Cake topping (5)
I believe the answer is:
icing
'cake topping' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for icing that I've seen before include "Cake frosting" , "in the freezer?" , "Cake-topper" , "effect of cold weather" , "that finishes off 29 [ANGEL CAKE]" .)