If the bleeding has stopped then you probably don't need to do anything. You can put a bit of plain neosporin on it or plain triple antibiotic ointment if you want to. Once the bleeding is stopped it will scab over, probably look black. As long as the other chicks don't peck at it, seeing blood, it should be ok. Blu kote can sometimes help disguise it if needed. Combs usually heal pretty fast.
It's not uncommon behavior for them to go after new, and unprotected chicks. When it's time to integrate brooder raised chicks I go slowly for gradually lengthening times, and supervise. I've had a couple over the years escape the nursery pen and get hurt also.