SE European fellow seen with another at bar (8)
I believe the answer is:
albanian
'se european' is the definition.
(Albania is in southeastern Europe)
'fellow seen with another at bar' is the wordplay.
'fellow' becomes 'al' (I've seen this in other clues).
'seen with another at bar' becomes 'banian' (I am not sure about this - if you are sure you should believe this answer much more).
'al'+'banian'='ALBANIAN'
(Other definitions for albanian that I've seen before include "of Balkan descent" , "Member of a Balkan people" , "Person from Tirana, say" , "Language used in Tirana" , "Eg, native of Tirana" .)