Strangely, or not so, yo can't assign witch robes as uniforms. Anyone know of a mod that will let me?

I'm not 100% sure, but I think the Wardrobe Wrangler might be able to do that. It's a seperate program you download and run from your desktop. You can use it to categorise clothing so there might well but a business uniform option but I can't find any documentation.

Here it is if you want to try it out. It's fairly easy to get your head around.
https://sims.jfade.com/index.php-ca...1&subcat=5.html