Possible Clues:

• Ceremony host, or a phonetic hint to 17-, 23-, 37-, 45-, and 58-Across
• Introducer of acts
• One running the show
• Run from a stage?
• Deejay, at times
• Open mic night host
• Seacrest on ''American Idol,'' e.g.
• Military Cross announced for host
• Figure at a roast
• ''Next up . . .'' speaker