Complex sentence: Fogelberg's second effort was much more successful--the 1974 Joe Walsh--produced album "Souvenirs" and its song "Part of the Plan" became Fogelberg's first hit.
Split into simpler sentences: Fogelberg's second effort was much more successful--the 1974 Joe Walsh-produced album "Souvenirs". The song "Part of the Plan" became Fogelberg's first hit.