Hickory nut (5)
I believe the answer is:
pecan
'hickory nut' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for pecan that I've seen before include "Walnut-like nut" , "Nutty type" , "Species of hickory - edible nut" , "Edible nut like a smooth walnut" , "of nuts" .)