Six-pack (abbr) (3)

I believe the answer is:

abs

(Other definitions for abs that I've seen before include "stopping system" , "Exercise to improve these" , "ratings?" , "Stomach muscles (abbr)" , "Some musculature" .)

I've seen this clue in The Guardian.

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.