Complex sentence: They made their U.S. debut appearance on Dick Clark's "American Bandstand" but broke-up in late 1986, whereupon Ridgeley moved to Monaco and tried his hand at Formula Three motor racing.
Split into simpler sentences: They made their U.S. debut appearance on Dick Clark's "American Bandstand". Following Wham!'s break-up in late 1986, Ridgeley moved to Monaco and tried his hand at Formula Three motor racing.