Cupboard contents including old copper tree (6)
I believe the answer is:
linden
'tree' is the definition.
(linden tree is a kind of tree)
'cupboard contents including old copper' is the wordplay.
'cupboard contents' becomes 'linen' (I can't justify this - if you can you should give a lot more credence to this answer).
'including' is an insertion indicator.
'old copper' becomes 'd' (historical abbreviation for penny).
'linen' placed around 'd' is 'LINDEN'.
Can you help me to learn more?
(Other definitions for linden that I've seen before include "One twigged" , "type of tree" , "Tree with Lea - also called 8" , "Unter den ------, iconic boulevard in Berlin" , "Lime tree" .)