A concluding article on humanity (4)
I believe the answer is:
amen
'humanity' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
'a concluding article' is the wordplay.
'concluding article' becomes 'men' (I can't justify this - if you can you should believe this answer much more).
'a'+'men'='AMEN'
'on' is the link.
Can you help me to learn more?
(Other definitions for amen that I've seen before include "Conclusion of prayer" , "Word at the end of a prayer" , "Response to prayer" , "I agree!" , "Final word in prayer" .)