Expect attitude after drink (7)
I believe the answer is:
suppose
'expect' is the definition.
(supposing is a kind of expecting)
'attitude after drink' is the wordplay.
'attitude' becomes 'pose' (I've seen this before).
'after' says to put letters next to each other.
'drink' becomes 'sup' (I've seen this before).
'pose' after 'sup' is 'SUPPOSE'.
(Other definitions for suppose that I've seen before include "Presume" , "Assume without proof" , "Expect" , "'Believe, perhaps on uncertain grounds (7)'" , "Put forward - imagine" .)