I personally would try to clean that up by using warm, damp compresses, try to get it as clean as you can, flush it out with sterile saline or diluted betadine. Then apply some plain triple antibiotic ointment in and on the wound. Reapply several times a day as needed to keep it covered in ointment. It may form a very thick scab as it heals. I agree that it may be rooster damage. If you have a rooster I would separate either her, or the roo from her, until she's healed up completely so that he doesn't re-injure it. I would also make very sure that no other flock mates are picking at it, which can happen with wounds. If either of those is happening then she needs to be separated (a wire crate in the coop or run with the others so they can still all see each other) works well and reduces stress from separation.