Refuse to acknowledge one's surrounded by drink (6)
I believe the answer is:
disown
'refuse to acknowledge' is the definition.
(I've seen this before)
'one's surrounded by drink' is the wordplay.
'one's' becomes 'is' (roman numeral).
'surrounded by' is an insertion indicator.
'drink' becomes 'down' (downing is a kind of drinking**).
'is' put into 'down' is 'DISOWN'.
(Other definitions for disown that I've seen before include "Reject all connection with, refuse to acknowledge" , "Repudiate, cast off" , "Disclaim or deny" , "Refuse to be associated with (something/someone)" , "Refuse to be associated with (a person)" .)