Толковый словарь английского языка Oxford English Reference - clue

n. & v. --n. 1 a fact or idea that serves as a guide, or suggests a line of inquiry, in a problem or investigation. 2 a piece of evidence etc. in the detection of a crime. 3 a verbal formula serving as a hint as to what is to be inserted in a crossword. 4 a the thread of a story. b a train of thought. --v.tr. (clues, clued, cluing or clueing) provide a clue to. Phrases and idioms clue in (or up) sl. inform. not have a clue colloq. be ignorant or incompetent. Etymology: var. of CLEW