Acknowledges it’s mad getting drunk (6)
I believe the answer is:
admits
'acknowledges' is the definition.
('admit' can be a synonym of 'acknowledge')
'it's mad getting drunk' is the wordplay.
'getting drunk' is an anagram indicator.
'its'+'mad'='itsmad'
'itsmad' is an anagram of 'ADMITS'.
(Other definitions for admits that I've seen before include "Concedes" , "Takes in" , "Agrees to the truth of something" , "Lets in and confesses" , "Owns up or lets in" .)