G.L.
I also have a child with sensory problems. He has only recently stopped biting his nails. In the past, he has made himself bleed ... which then sets off a different sensory episode ......
According to our Occupational Therapist, he was seeking oral stimulation. Chewing gum is a good alternative (you have to choose sugar or or artificial sweeteners ..(both evil in their own ways). Another idea was to provide food or medical grade tubing for him to chew on. Example - IV tubing or straws that come with some "sippy cups".
My son also hated clippers. When he was four he discovered that a plastic rhinocerous gave him the courage to withstand getting his toenails clipped (he never needed his fingernails clipped since he chewed them ..). He would hold the rhino and let it growl and snort at me while I clipped ... Maybe you can find something to help your daughter find courage for the time of clipping ... or if it is only the sound that bothers her, let her try listening to music on headphones while you clip or file.
There is a lot of information on sensory processing disorders on the web now. And a publication called S.I. Focus. This might be of interest to you at home and professionally!
Good luck.
GLerner