Pecan or filbert (3)
I believe the answer is:
nut
I believe this is a double definition.
'pecan' is the first definition.
(I've seen this in another clue)
'filbert' is the second definition.
(I've seen this in another clue)
(Other definitions for nut that I've seen before include "Mechanical fastener" , "Fruitcake" , "1A [CRACKPOT]?" , "Obsessive enthusiast" , "Almond, for example" .)