Related Clues:

• Smiley, Smart or Solo
• He'll eventually rat you out
• Stinger?
• Traffic stopper, for short
• MI6 member
• Person with intelligence
• Use a hidden camera, say
• Hush-hush job
• CIA employee
• Infiltrator
• DEA agent, e.g.
• Observe covertly
• Dealer's bane
• Fuzz buster?
• Emulate a peeping Tom