"I 100% agree!" (4)

I believe the answer is:

amen

(Other definitions for amen that I've seen before include "Prayer ending" , "Prayerful last word" , "Conclusion of prayer" , "Name for prayer's end" , "Last word of prayer" .)

I've seen this clue in the USA Today.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.