Supposed to be a piece of wood out of a tree (6)
I believe the answer is:
opined
'supposed' is the definition.
(I've seen this before)
'a piece of wood out of a tree' is the wordplay.
I cannot really see how this works, but
'piece' could be 'pin' (pin is a kind of piece) and 'pin' is found within the answer.
'of' could be 'o' and 'o' is found in the answer.
The remaining letters 'ed' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'to be' acts as a link.
Can you help me to learn more?
(Other definitions for opined that I've seen before include "Conjectured" , "Gave as view or thought" , "Gave as one's view" , "Supposed" , "Expressed as one's belief" .)