Related Clues:

• Legal defense mechanism?
• 'I was at the movies - nowhere near the crime,' e.g
• It could be ironclad
• Suspect's way out
• "I was home alone," perhaps
• One may be cast-iron
• Whodunit story?
• It's just an excuse
• Proof of not being at crime site
• 'I was home alone,' perhaps
• It may be ironclad
• Whodunit excuse
• A politician once needing independent defence in law
• Courtroom clearer, perhaps
• Thin Lizzy was "Waiting for" one