I have a few questions that might make it easier for us to offer you some advice:
- is she an established member of the flock, and if so, where is she normally in the pecking order?
- how many hens have you got in your flock, and are they all picking on her, or just one or two of them?
- how long has she been broody, and is she sitting on fertile eggs?
- is it her first time brooding, or has she done it before? (if so, was it a successful brood?)
- do you want her to continue brooding or would you prefer to stop her?
- have you got a safe place (outhouse / shed / garage etc.) where you could set up a temporary area for your broody and her eventual chicks?
The more information you can give us about your setup, the easier it will be for people to help you.