Related Clues:

• 'You there!'
• "Hey, Mister!"
• Green-light indicator
• Clandestine signal
• Surreptitious sound
• "Hey, Mac!"
• Silent okay
• Sotheby's signal
• Sleep unit?
• Land east of Eden
• Secretive attention getter
• Okay
• Sign of approval
• Fence’s utterance
• Auction gesture