Complex sentence: Although Jean had no aspirations for a theater career, she was asked to replace an actress and entered on the vaudeville Keith-Albee-Orpheum circuit with boyfriend Dan Jarrett.
Split into simpler sentences: Although Jean had no aspirations for a theater career, she was asked to take the place of an actress in an established act with her boyfriend. She went on the vaudeville Keith-Albee-Orpheum circuit with Dan Jarrett.