Kidney-shaped nut (6)
I believe the answer is:
cashew
'kidney-shaped nut' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for cashew that I've seen before include "Edible nut" , "Acajou" , "snack perhaps" , "Chew as you would this nut" , "nut-tree" .)