Related Clues:

• Gary Cooper's refusal to work in Tyneside
• Denial honest, then back to front
• "Ain't gonna happen!"
• "Guess again"
• "Nuh-uh"
• "Nah!"
• Terse negative
• "You're dreaming"
• Slangy denial, and a hint to 20-, 29-, 46- and 56-Across
• "Not a chance"
• 'ÔFraid not'
• "Won't do it"
• 'Not gonna happen!'
• Uncouple every other one? Not on your life!
• Negative response of number needing exercise