Hollow stem of wood (4)
I believe the answer is:
cane
'hollow stem of wood' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for cane that I've seen before include "Type of sugar; beat" , "Slender support, for 32 across say" , "Bamboo, sugar, stem" , "Sugar plant" , "A light rod once used for punishment" .)