Maybe bitter about situation, as Peter was? (7)

I believe the answer is:
apostle
'peter was?' is the definition.
I can't tell whether this definition defines the answer.
'maybe bitter about situation' is the wordplay.
'maybe bitter' becomes 'ale' (type of beer or bitter. I am not sure about the 'maybe' bit.).
'about' is an insertion indicator.
'situation' becomes 'post' (both can mean a job or position).
'ale' enclosing 'post' is 'APOSTLE'.
'as' is the link.
Can you help me to learn more?
(Other definitions for apostle that I've seen before include "Evangelist, proponent" , "Peter, perhaps" , "One of Christ's 12 original disciples" , "Thaddeus, perhaps" , "Vigorous campaigner" .)
