Nut of the hickory tree (5)
I believe the answer is:
pecan
'nut of the hickory tree' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for pecan that I've seen before include "Walnut-like nut" , "Oval nut of south central United States" , "Smooth pinkish-brown nut, nice in pie" , "of nuts" , "Nut of American hickory tree" .)