Nut-bearing tree (5)
I believe the answer is:
beech
'nut-bearing tree' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for beech that I've seen before include "Common forest tree" , "Nut-bearing tree" , "Copper or silver tree" , "Tree with bitter 'nuts'" , "for mast?" .)