Related Clues:

• Profoundly different
• Square-root sign
• Far beyond the norm
• Pugnacious
• Vigorous campaigner
• "Far out!"
• Committed
• Extreme, ultra
• Full of earnest enthusiasm
• Of reform, fundamental and innovative
• One who favours thoroughgoing reform
• Going to the roots, fundamental as change may be
• One who works energetically as in politics
• Pugnacious, eager to fight
• Person with extreme political views