Related Clues:

• Defense, perhaps
• Crossword hint
• Bit of evidence
• Sleuth's need
• Legal defense
• Grounds
• Burglary, for one
• ''I was at home sleeping at the time,'' e.g.
• It might be airtight
• Reason
• Fiction genre
• Crossword feature
• Idea
• Defendant's defense
• Likely story?