Transplant set heavy drinker back (5)
I believe the answer is:
repot
'transplant' is the definition.
(I've seen this before)
'heavy drinker back' is the wordplay.
'heavy drinker' becomes 'toper' (I've seen this before).
'back' shows that the letters should be reversed in order.
'toper' back-to-front is 'REPOT'.
'set' acts as a link.
(Other definitions for repot that I've seen before include "plant in another location" , "Move plant" , "place somewhere new to put down roots" , "Transplant" , "to fit into new container" .)