I just had to do the same thing with Brody and the power drill. He is fear aggressive, so instead of running away and hiding, he runs toward and barks. He will try to bite, too, if he gets the chance. He will still attack the vacuum cleaner sometimes, if I don't have the treats ready. So I was installing magnetic catches on my old kitchen cupboards, and Brody was running up and barking and trying to bite the drill every time I ran it. I got a handful of treats and put them on the floor beside me and asked Brody for a down. I gave him a warning before I started, "ready?", then started drilling. If he stayed quiet, I tossed him a treat. If he barked or broke his down, no treat. If your little student's owner is with you, you might have them either do the clicking or the treating while you do the other job, just until she realizes that the click means treat. That way the clicker can be further away from her. You might have to toss the treats to her if she really has to run and hide. I had to do that with the coffee grinder and the vacuum cleaner at first, because he would only be quiet when he was at a distance. Now he follows me around when I vacuum, and sits on the floor next to me when I grind coffee. Or use the power drill!