Source of chocolate (5)
I believe the answer is:
cacao
'source of chocolate' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for cacao that I've seen before include "Tree yielding chocolate" , "Tree with seeds used to make chocolate" , "Tree for cocoa bean" , "Tropical tree, the source of chocolate" , "Bean providing chocolate" .)