Related Clues:

• One who may bug you
• 'The X-Files' extra
• Role getter, perhaps
• Sales pro
• Artist's negotiator
• Person with a code name, maybe
• Unwelcome plant?
• Smart or 99, e.g.
• Valerie Plame, e.g.
• Espionage expert
• Mole, e.g. 19. Thumbs-down vote
• One may be double or free
• Author's rep
• Double agent, e.g.
• U-2 pilot, e.g.