1) Instrumentalist 2) Ma is one 3) Member of a string quartet 4) Musician 5) Pablo Casals 6) Player 7) Room first for musician 8) Some who plays a violoncello 9) String player 10) String quartet player 11) Stringed-instrument player 12) Yo-Yo Ma Found on https://www.crosswordclues.com/clue/cellist