Related Clues:

• Private eye, for short
• Magnifying glass carrier, maybe
• Listen in (on)
• P.I., e.g.
• Mr. Moto, e.g.
• Peeper
• Dick
• Detective
• One may follow a lead
• 16-Across, to some
• Nosy sort
• Satirical magazine
• Nosey Parker
• Sleuth, for short
• See 9-Across