If you are selling just that one item BNWT it should be OK.
This is eBay's blurb on what is accepted in this new free seller free offer:
What are pre-owned clothes?
Pre-owned clothes are items you no longer want or need in a variety of conditions, for example an outfit that no longer fits, an unwanted gift, or vintage fashion that needs a new home. These items can be new or used. Selling clothing for free on eBay is a great way to make some extra cash.
