Related Clues:

• Last word of an ultimatum, perhaps
• ''Do it, or ___!''
• In __ of (replacing)
• Where starter
• In -- of (as a substitute for)
• ''Or ___!''
• See 21 Across
• In __ of (instead of)
• ''Will there be anything __?''
• ''What ___ can go wrong?''
• In __ of: to replace
• "Who ---?"
• 'So what -- is new?'
• Choice introducer
• Other than me