Complex sentence: Because Musin never joined the Communist Party of the Soviet Union, his conducting career was curtailed by the Soviet government; he then channelled his creative output into pedagogy, creating a school of conducting, still referred to as the "Leningrad conducting school".
Split into simpler sentences: Because Musin never joined the Communist Party of the Soviet Union, his conducting career was curtailed by the Soviet government. He channelled his creative output into pedagogy, creating a school of conducting that is still referred to as the "Leningrad conducting school".