Possible Clues:

• Lead singer on "The Joshua Tree"
• Lead singer on 'The Joshua Tree'
• Chaz (nee Chastity)
• First musician to be a ''Time'' Person of the Year
• Pro ___ (gratis)
• Pro ___ (at no charge)
• Singer who works close to The Edge
• Rock singer who was a Time co-Person of the Year
• U2's star vocalist
• 'I Still Haven't Found What I'm Looking For' singer