Related Clues:

• Agent 'embedded' in this puzzle's theme answers
• Work under cover, in a way
• Invisible ink user
• One wearing a wire, perhaps
• Word repeated in Mad magazine's '___ vs. ___'
• Telephoto-lens user, perhaps
• Use binoculars, perhaps
• 'Mission: Impossible' figure
• Smiley or Smart
• Bond, e,g.
• Quisling
• Napoleon Solo, e.g.
• Spy plant
• Cloak-and-dagger figure
• Pesky yard critter