Related Clues:

• Tell (on)
• Be a stool pigeon
• Tell a secret
• Rat, so to speak
• Tell all, slangily
• Do lullabies, e.g.
• Be a squealer
• Give away a secret
• Rat someone out
• Perform 2-Down
• Join the choir
• Perform with a choir
• When doubled, a New York prison
• Perform on 'American Idol,' e.g.
• Take the mic