Hi - I have only just joined, so I hope its OK to post.
If anything is "hanging off" then probably best cut it away. I had a small chick damaged all its toes, and I snipped them with some nail nippers, but maybe some very sharp secateurs or a very sharp strong knife on a cutting board.
Wash and disinfect the wound, and dry then put on some antiseptic powder. Leave it alone in a dark place to recover, making sure it drinks water from time to time. I would put some homeopathic Arnica 30c and Aconite 30c in the water, and a few drops of Bach's Rescue Remedy.
If when you put it back with the others there is any pecking then Stockholm tar on the wound should stop any more pecking, and help protect and disinfect the wound.
all the best
Sue