clue noun

ADJ. good, important, useful, valuable | vital | tell-tale | obvious

VERB + CLUE have, hold So far, the police haven't got any clues as to the motive for the crime. Diet may hold the clue to the causes of migraine. | give (sb), furnish/provide/supply (sb with), yield The hat gives a clue to the identity of the killer. The letter yielded no clues. | hunt for, look for, search for | discover, find, uncover | leave The burglar left no clues. | follow (up)

PREP. ~ about This research might provide an important clue about how cancer develops. | ~ (as) to a clue as to her whereabouts