Semicircular recess, or moon-shaped case used at Mass? (7)

I believe the answer is:

lunette

(Other definitions for lunette that I've seen before include "Crescent-shaped space" , "Something crescent-shaped" , "fortification" , "Crescent-shaped ornament" , "Towing-ring; crescent shape" .)

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.