One joining in the chorus (4)

I believe the answer is:

alto

(Other definitions for alto that I've seen before include "Member of choir" , "One who sings" , "Low female singing voice" , "someone to sing" , "Male singer" .)

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.