Mexican sauce flavored with chocolate (4)
I believe the answer is:
mole
'mexican sauce flavored with chocolate' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for mole that I've seen before include "Skin spot; breakwater" , "A spy within an organisation" , "Spot - burrowing mammal" , "Underground worker!" , "Naevus - burrowing mammal - spy" .)