In the entry for “cloaca” it traces it back to the PIE root *kleu- meaning to clean.
However, the entry for *kleu- gives a different meaning, to hear. Is this a different PIE root or is it an error?
The etymonline entry doesn’t link to the entry for that root. So it does not intend you to trace back to it. The PIE roots are reconstructions. On any list of them you’ll find many that look identical.