Top of class found with a drink is expelled (4,3)
I believe the answer is:
cast out
'is expelled' is the definition.
(I've seen this before)
'top of class found with a drink' is the wordplay.
'top of' suggests taking the first letters.
'found with' means one lot of letters go next to another.
'drink' becomes 'stout' (type of beer).
The first letter of 'class' is 'c'.
'c'+'a'+'stout'='CAST OUT'
(Other definitions for cast out that I've seen before include "Rejected from a group" , "Expel" , "Expelled" .)