Cashew or pecan (3)
I believe the answer is:
nut
I believe this is a double definition.
'cashew' is the first definition.
(I've seen this in another clue)
'pecan' is the second definition.
(I've seen this in another clue)
(Other definitions for nut that I've seen before include "Fruit with hard case" , "Large, hard-shelled seed" , "Cashew or hazel" , "Screwing block" , "Hard fruit or informal lunatic" .)