Drop everything! I have just discovered that clue originally meant "a ball of yarn". Thread, the very stuff that Ariadne told Theseus to dangle after him through the labyrinth. Wow, gosh, and gee-whizzelly-wee! And this, all the better because yarn is also a synonym for story. There were those who thought I shouldn't bother getting out of bed this morning, but you shewed them, Poxford English Dictionary, oh yes you did.