How to get that last foot trimmed?

I have a 3/4 Percheron 1/4 mustang 4year old mare that I bought in November last year. She hadn't been handled much and the previous owners said the last farrier only got to 2 of her feet and said she was fighting to much. I worked with her and got her used to having her feet picked up/out, before i called the farrier. It took over an hour and a half to get all 4 feet trimmed and on the last one her right hind she was pretty much done with us. But I've had him out 3 times since then and she wont even let him get close to the right hind, she has takin to warning kicking even. He can get the other 3, but not that 1. I regularly pick her hooves and she's fine with all of them. I don't know what else to do. I've had my brother and boyfriend pick it up and she is slightly hesitant, but will pick it up.