Buy polish off singer who’s often high (7)
I believe the answer is:
swallow
This clue could be a double definition.
'buy polish' is the first definition.
'swallow' can be an answer for 'buy' (swallowing is a kind of buying). I am not sure about the 'polish' bit.
'singer who's often high' is the second definition.
(swallow is a type of songbird)
'off' acts as a link.
Can you help me to learn more?
(Other definitions for swallow that I've seen before include "Songbird" , "Take in - migratory bird" , "Buy < and consume" , "Accept" , "Creature which can go up" .)