Nowadays, we know a “clue” to be something that reveals information or serves to solve a problem. However, there is quite a yarn to be spun as to how we got here.
You see, “clue” is an orthographical shift from a Middle English term, “clewe”, and Old English “cleowen” before that, which translates as a ball of yarn. This can be traced back to Proto-Germanic and has modern parallels with German and Dutch words – which is why we might not expect the origin to come from Greek mythology.
According to the myth, on the island of Crete, there was a labyrinth in which dwelled a half-man, half-bull creation called the Minotaur. This creature was the offspring of the king of Crete, Minos’ wife, Pasiphaë, and a bull – no, me neither – and naturally the former wasn’t too pleased about this genetic cocktail. Naturally, a hero pops up to deal with said beast, Theseus.
It was well established that finding one’s way through the labyrinth was a bit confusing, ergo Ariadne, daughter of Minos, supplied Theseus with a ball of string with which he could leave a trail to find his way back out. Retrospectively, English speakers later on would refer to this ball of string as a ““clewe” and so it begins.
As a side note, “Minotaur” comes from “Minos” (eponymous with the chap himself) and Greek “Tauros”, meaning “bull” – not to be confused with your zodiac sign, which is actually Latin.
It is from this kind of specific context and particular meaning that words often develop symbolic connotations, and in this case that meant that the little ball of yarn came to represent a helping hand in all manner of mysteries and malfunctions, becoming the term we use today.
The first known usage of “clue” with its modern definition comes in the rather verbose Logick: Or, The Right Use of Reason in the Enquiry after Truth by Isaac Watts in 1724;
When the Reader is passing over such a Treatise, he often finds a wide Vacancy, and makes an uneasy Stop, and knows not how to transport his Thoughts over to the next Particular, for Want of some Clue or connecting Idea to lay hold of.Isaac Watts, 1724