Related Clues:

• "Ain't gonna happen!"
• Not in any way, in dialect
• Not under any circumstances, informally
• "Guess again"
• "Nuh-uh"
• Not at all, in the sticks
• "Nah!"
• Terse negative
• "Never in a million years!"
• Sounds like expertise? Never, not in any way!
• Negative response to what Indian says? That's to emphasise what's negative!
• "Absolutely not!"
• "You're dreaming"
• Slangy denial, and a hint to 20-, 29-, 46- and 56-Across
• "Not a chance"