Related Clues:

• Backup cause
• Stuff up
• Fallback scheme
• Canon function
• Choke up
• Keep from draining
• Sink problem
• Obstacle to progress
• Cheat on a test, in a way
• Job for a drain cleaner
• Backup cause, often
• Get stopped up
• Fallback provision
• Plumbing stop-up
• Try this if things don't work out