Possible Clues:

• 'Just one thing, or one that is not agreeable (8)'
• One thing or one is not agreeable
• Protester
• Aim for gold? I disagree
• Where there's a thing, or one is not agreeable
• Opposing counsel, at times
• One protesting
• He may be conscientious in his protests
• One who won't accept goal starts to offend referee
• One who opposed something, or supports