The 44-year-old Clark, nicknamed "Boo Boo" by his grandfather, began his career at Evangeline in 1975. In that year, he recorded 13 wins, 22 seconds, and 15 thirds in 165 mounts. In 1977, he switched his tack to the Nebraska circuit. He captured his first black-type stakes win aboard Spark d'Or in the Columbus Futurity in 1977. On Oct. 14, 1989, Clark scored the biggest win of his professional career as he guided the Vanier trained Western Playboy to convincing 17-length victory in the $300,000 Pennsylvania Derby at Philadelphia Park. Clark also rode multiple stakes winner Dispersal, and was the regular workout rider for Kentucky Derby (gr. I) winner Unbridled, Gate Dancer, Gilded Time, and Sefa's Beauty.
When asked how much longer he plans to ride, Clark said: "I am a believer in hard work, and I want to see it payoff. Sometimes, it does in this game and other times it doesn't. Right now I am having fun and, the good Lord willing; I will do it as long as it stays fun."