I have been clean of weed for 23 days bought a take home drug test and failed, how much longer will it take to clear?

Often a long time: Unfortunately for everyone, cannabis stays on board much longer than drugs that are much more dangerous. It's stored in body fat and if you're dieting / exercising, it can be released months later. If you do test positive, it is likely to be at a low level and you might perhaps attribute it to passive exposure, or that you were in a jurisdiction where it was legal.