Possible Clues:

• Gee horse (anag.)
• Warning of impending action, say, welcomed by men of courage
• Let's begin!
• I'm about to begin - ready, steady . . . . . . . .
• I'm starting, say, to get into Ivanhoe and the like
• Informally, I'm about to begin
• Words before a skydive, perhaps
• Words before a stunt
• One's about to start getting clothes and stockings for Spooner
• Words of daring, say, embraced by champions