Related Clues:

• Holler in the hills
• Refrain from the mountains
• When doubled, a New York prison
• Perform on 'American Idol,' e.g.
• Warbler's sound
• Take the mic
• Do some karaoke
• Emulate Justin Bieber
• Rat on the Mob
• Alps song
• Belt one out
• Coloratura's vocal effect
• Produce some cliff notes?
• Participate in karaoke
• Call across vales