It brings one to a devout conclusion (4)
I believe the answer is:
amen
This could be a double definition.
'it brings one to a devout' is the first definition.
The definition suggests a singular noun which matches the answer.
'conclusion' is the second definition.
(I have seen 'Conclusion of prayer' mean 'amen' so perhaps 'conclusion' could also mean 'amen')
Can you help me to learn more?
(Other definitions for amen that I've seen before include "Word at the end of a prayer" , "Approve" , "statement of affirmation" , "Extremist" , "I agree!" .)