Complex sentence: At age 14, he enrolled in the army as a Boy Musician in order to continue his musical studies of the clarinet and harp, then saxophone, touring with some of the top British bands of the era.
Split into simpler sentences: At age 14, he enrolled in the army as a Boy Musician in order to continue his musical studies of the clarinet harp, and saxophone. Following this, he toured with some of the top British bands of the era.