Welcome to BYC.
Can you post a photo of the injury?
When you say that she is getting stronger, was the cut infected and cause her to become weak, was she limping badly etc.?
How long did you have her isolated?
If she was isolated for a few days and was not in sight of the rest of the flock they most likely view her as an "intruder". You will need to try to slowly re-integrate/re-introduce her back into the flock. There are several article here on BYC about how to go about this. One way is a see-but-don't-touch method. Place her in a wire kennel inside the run with her own food/water. That way she is safe, the others can see her. Sprinkle a few treats around the cage (give her some too) so they are all "eating" close to each other. You will need to do this for several days until you feel comfortable that she can defend herself and that the others have somewhat accepted her. Let her out with supervision and see how it goes. It may take more than one try. Patience is your friend.
After a period of introduction if they still attack her, then you may need to reevaluate her health. A weak/sick chicken will generally be repeatedly attacked, they are most likely viewed as a "threat" to the welfare of the flock.
