Related Clues:

• Professor Plum's game
• Tip
• Shoe impression, maybe
• Part of a crossword
• Colonel Mustard's game
• Lead
• Tip-off
• 'Get a ___!'
• Help for Nancy Drew
• Hint
• Indication
• One of 39-Across
• Fingerprint or dropped handkerchief, say
• This, for example
• Detective's need