Answer people, having the last word (4)
I believe the answer is:
amen
'having the last word' is the definition.
(I've seen this before)
'answer people' is the wordplay.
'answer' becomes 'a' (abbreviation eg in Q and A).
'people' becomes 'men' (man is a kind of person**).
'a'+'men'='AMEN'
(Other definitions for amen that I've seen before include "Approve" , "Word of approval" , "I agree!" , "Word of agreement" , "prayer's ending" .)