... bishops perhaps after a final word (4)
I believe the answer is:
amen
'final word' is the definition.
(I've seen this before)
'bishops perhaps after a' is the wordplay.
'bishops perhaps' becomes 'men' (bishop is a kind of man).
'after' means one lot of letters go next to another.
'men' put after 'a' is 'AMEN'.
(Other definitions for amen that I've seen before include "Word of approval" , "Word at the end of a prayer" , "Extremist" , "I agree!" , "Religiously 11 [THE LASTWORD]" .)