Vegan protein source (5)
I believe the answer is:
beans
'vegan protein source' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for beans that I've seen before include "Edible kidney-shaped seeds" , "Haricots, e.g." , "Haricots for instance" , "Coffee seeds" , "Vegetables" .)