Long period at the top of eg show business

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
"upper reaches of a profession or pursuit," c.1910 from vaudeville slang; the phrase was common in colloquial use late 19c.-early 20c. in a broad range of senses: "party, shindig, fun, frolic."

Wikipedia Word definitions in Wikipedia
Big Time is a 1929 film starring Lee Tracy and Mae Clarke as a show business couple who break up over his infidelity. This was Clarke's film debut. Director Kenneth Hawks was Howard Hawks ' brother.

WordNet Word definitions in WordNet
n. the highest level of an occupation (especially in entertainment)