I had observed this lady in my office swindle people around with her gossip and blackmail combine with lies each time you confront her. right now her sight pisses me off. but cos of work ethics I still had to relate with her from time to time regarding work related issues.
As long as she has no dirt on you I would bring it to your boss and discuss it with her and your boss and if she isn't fired at least she will know her boundries with you and consider her job the next time she starts the he said she said.... that's if you care if you don't fire her. I'm sure someone like that has pleanty of reason to get fired. If she does have dirt on you wait it out shell piss the wrong person off soon enough... best to you
With her being a subordinate, that is a hard one. Remember the old saying, "niceness kills" and "you get more with honey than you do with spice". Put that mask on and do what you have to do.