Related Clues:

• Utter repetitively
• Intonation
• Join the rat race
• Root words?
• Monk music
• "USA! USA!" is one
• Put in one's eight hours
• Nine-to-five routine, and hint to this puzzle's theme
• Street protest sound
• Sing a simple song
• Protesters' sound
• Protesters' chorus
• Nine-to-five routine
• Unison cheer (1894)
• 'USA!' e.g.