Related Clues:

• __ running: more-than-a-marathon race
• Prefix with sonic
• With 20-Across, 'Well done!'
• Very, and then some
• Prefix meaning 'very'
• How Eric Carle diagnosed his caterpillar?
• Extremely foul tramp’s lost outside
• Prefix for 'sound' or 'marathon'
• Radical type
• Uber-
• Prefix with violet or marine
• Extremist cults pray, having lost all protection
• Prefix for 'sonic'
• "Extreme" prefix
• Prefix for "sound"