Related Clues:

• Line in speech? Indeed
• Maestro's signal
• Actor's hint
• It can be chalked up
• White ball on slate
• Slamming door, perhaps
• It's often behind the eight ball
• It's used in snooker and on stage
• A wink or a nod, maybe
• Hint coming from line, we hear
• Stick with a blue tip, maybe
• Signal to go on, say
• Entrance signal
• Banking instrument?
• Prompt's prompt