Purchased branch on top of tree (6)
I believe the answer is:
bought
'purchased' is the definition.
('buy' can be a synonym of 'purchase')
'branch on top of tree' is the wordplay.
'branch' becomes 'bough' (bough is a kind of branch).
'on top of tree' becomes 't' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'bough'+'t'='BOUGHT'
Can you help me to learn more?
(Other definitions for bought that I've seen before include "Purchased" , "paid for" , "Puchased" , "Obtained" .)