Related Clues:

• At the ready
• Sound from an exam cheater
• "Want to hear a secret?"
• Listen!
• Far from sleepy
• Bright-eyed and bushy-tailed
• Advance warning
• Verbal jab in the ribs
• 'You there!'
• "Hey, Mister!"
• Clandestine signal
• Watching
• Surreptitious sound
• Quick on the uptake
• Listen closely