Related Clues:

• Scuttled mission
• "Doubt it"
• "I'll pass"
• 'Uh uh!'
• Informal turndown
• Something off-limits
• Familiar denial
• ''The deal is off!''
• ''Never mind''
• Inoperative, at 14-Across
• 'Mission aborted'
• 'Don't wanna'
• 'Never gonna happen'
• Nixed, at NASA
• "Count me out"