Related Clues:

• Was a rat
• Turned state's evidence
• Named names
• Blabbed to the feds, say
• Belted out
• Was in a choir
• Acted the fink
• Squealed
• Joined the choir
• Tried out for "American Idol"
• Acted the stoolie
• Went caroling
• Ratted
• Was a fink
• Did a number