My mare is good to clip except when it comes to clipping her lower mandible (chin groove) She will strike out to try and knock clippers out of your hand. Wonder if she finds the clipper vibration too much?
sounds like she has 'electric' whiskers. some have static and get a mini shock when clippers touch whiskers (like you can get off a car door!).... best to trim them off by hand with a razor or scissors. this usually solves the problem and then you can clip the chin relatively easily after.