A Clue

1. (now rare) A strand of yarn etc. as used to guide one through a labyrinth; something which points the way, a guide.
2. Information which may lead one to a certain point or conclusion.
3. An object or a kind of indication which may be used as evidence.
4. Insight or understanding ("to have a clue [about]" or "to have clue". See have a clue, clue stick)

Synonyms

• (information which may lead one to a certain point or conclusion): hint, indication, suggestion
• (object or indication which may be used as evidence): signature
• (understanding): idea