Steering apparatus in hard wood (4)
I believe the answer is:
helm
'steering apparatus' is the definition.
(I've seen this before)
'hard wood' is the wordplay.
'hard' becomes 'h'.
'wood' becomes 'elm' (elm is a kind of wood**).
'h'+'elm'='HELM'
'in' acts as a link.
(Other definitions for helm that I've seen before include "Position of steerer" , "Position of leadership" , "Steering mechanism" , "Wheel that controls ship's rudder" , "part of boat near stern" .)