It allows for venting (4)

I believe the answer is:

slit

(Other definitions for slit that I've seen before include "Narrow straight cut or opening" , "Long straight cut" , "Incision" , "Long narrow opening" , "Long narrow cut" .)

I've seen this clue in The New York Times.

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.