Last word from atomic team (4)
I believe the answer is:
'last word' is the definition.
(last word in a prayer)
'atomic team' is the wordplay.
'atomic' becomes 'a' (eg in A-test, atomic test).
'team' becomes 'men' (group of people).
'from' is the link.
(Other definitions for amen that I've seen before include "Religiously 11 [THE LASTWORD]" , "Final word in prayer" , "Extremist" , "Put name to end of payer" , "Word of approval" .)