Plant once again lush, climbing (5)
I believe the answer is:
repot
'plant' is the definition.
(I know that repot is a type of pot)
'lush climbing' is the wordplay.
'lush' becomes 'toper' (both can mean an alcoholic).
'climbing' shows that the letters should be reversed in order (in a down clue, letters climb up).
'toper' back-to-front is 'REPOT'.
'once again' acts as a link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for repot that I've seen before include "to fit into new container" , "transfer seedlings" , "Move plant" , "Give room to expand" , "place somewhere new to put down roots" .)