Light dessert (6)
I believe the answer is:
mousse
'light dessert' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for mousse that I've seen before include "Whipped sweet" , "Creamy dessert; hair dressing" , "Frothy creamy substance for styling hair" , "Frothy, creamy dessert" , "cold dish" .)