What was the name of Mark Twain's daughter who became a concert singer?

Mark Twain's daughter who became a concert singer was Clara Clemens.

Born Clara Langhorne Clemens in 1874, she was the second of Mark Twain and Olivia Langdon Clemens's three daughters. Her older sister was Susy, and her younger sister was Jean; the couple also had a son, Langdon, who died in infancy. Clara grew up in a literary household shaped by her father's fame and her mother's editorial influence.

Clara developed her voice in Europe, spending part of her youth in Vienna and studying music with prominent teachers. She also studied piano under Theodor Leschetizky, who had taught other important musicians. Her professional career focused on singing, especially as a contralto.

She made her American concert debut in Norfolk, Connecticut, on September 22, 1906. She later performed in London and Paris, sometimes in benefit concerts. Clara is sometimes remembered only as Twain's daughter, but she also managed his estate and protected his literary legacy after his death in 1910. She was his only surviving child when she died in 1962.