Judas for one bitter about situation (7)
I believe the answer is:
apostle
'judas for one' is the definition.
(judas is a kind of Apostle)
'bitter about situation' is the wordplay.
'bitter' becomes 'ale' (type of beer or bitter).
'about' is an insertion indicator.
'situation' becomes 'post' (both can mean a job or position).
'ale' going around 'post' is 'APOSTLE'.
(Other definitions for apostle that I've seen before include "John, perhaps" , "Thaddeus, perhaps" , "Ardent espouser of new system" , "Missionary or evangelist" , "Vigorous supporter" .)