Brittle sweet (12)
I believe the answer is:
butterscotch
'brittle sweet' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for butterscotch that I've seen before include "Brittle, yellow-brown sweet" , "confectionery" , "Hard brittle toffee" , "Type of toffee" , "Kind of toffee" .)