Imagines attitudes after drink (8)
I believe the answer is:
supposes
'imagines' is the definition.
('suppose' can be a synonym of 'imagine')
'attitudes after drink' is the wordplay.
'attitudes' becomes 'poses' (I've seen this in other clues).
'after' is a charade indicator (letters next to each other).
'drink' becomes 'sup' (I've seen this before).
'poses' put after 'sup' is 'SUPPOSES'.
(Other definitions for supposes that I've seen before include "Thinks, imagines" , "Imagines to be true" .)