Complex sentence: His father was a prosperous linen merchant, who entrusted Jommelli to study music under Canon Muzzillo, the director of the Aversa cathedral choir.
Split into simpler sentences: His father was a prosperous linen merchant, who entrusted Jommelli to the choir director of the cathedral, Canon Muzzillo. Jommelli studied music under Canon Muzzillo, the director of the Aversa cathedral choir.