Hymn finale (4)
I believe the answer is:
amen
'hymn finale' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for amen that I've seen before include "Word of approval" , "Name for prayer's end" , "Approve" , "Religiously 11 [THE LASTWORD]" , "as agreed!" .)