clew (n.)

"ball of thread or yarn," northern English and Scottish relic of Old English cliewen "sphere, ball, skein, ball of thread or yarn," probably from West Germanic *kleuwin (source also of Old Saxon cleuwin, Dutch kluwen), from Proto-Germanic *kliwjo-, perhaps from a PIE *gleu- "gather into a mass, conglomerate," from the source of clay (q.v.). For further sense evolution, see clue (n.).