What I like to do is,
(sorry if sombody said this already, didnt read all of them

)
Turn on the clippers and start rubbing my horse with my HAND
So it will calm her down a little bit
I do this a couple of times and so I start getting closer with the clippers but yet not touching her
So I keep talking to her to calm her down a pat on the neck
And well this what happend to MY horse, I just did this a couple of times and she alowed me to let me clip her
But heres the thing, my horse isnt THAT affraid of the clippers