Crossword Genius

Proves one's peccability (4)

Ross

I believe the answer is:

errs

(Other definitions for errs that I've seen before include "Goes astray" , "Goes wrong" , "Makes mistakes" , "Makes a mistake" , "Strays" .)

I've seen this clue in the Newsday.
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.