Related Clues:

• Member of the opposition
• Aircraft beginning
• Contrarian
• One set against
• Inflammatory prefix
• Hostile one
• Contrarian, e.g.
• Foe's position
• Pro's foe
• Not supporting
• Not for
• Less-than-climactic start?
• The "A" of ABM
• Knock or social preceder
• Nay voter