Adhere to a bit of wood (5)
I believe the answer is:
stick
I believe this is a double definition.
'adhere' is the first definition.
(I know that adhere can be written as stick)
'bit of wood' is the second definition.
(a stick is a bit of wood from a tree)
'to a' acts as a link.
(Other definitions for stick that I've seen before include "School punishment once" , "Baton; gum" , "Join firm" , "Glue; piece of wood" , "See 2" .)