Related Clues:

• Not a pro
• Picketer, perhaps
• Prefix with proton or ballistic
• Prefix with hero or matter
• Negative prefix
• Opposing side
• One of the opposition
• Apt to say nay
• Opposed one
• Prefix with thesis
• Dissenter's position
• Climax beginning
• Matter or hero prefix
• In a negative camp
• Member of the opposition