Clothing can be patented. Most of the time, you would patent the unique design of your apparel with a design patent. This is because you are claiming invention of the unique look of the clothing and not the clothing itself.
Clothing companies will often patent a unique design to prevent other companies from imitating it. If you hold design patent rights, you could sell or license them to a clothing company.
If your apparel has unique functions to it, you could also patent those functions with a utility patent. In 2008, Katerina Plew sued Victoria's Secret for patent infringement over their "Very Sexy 100-Way Strapless Convertible Bra." Plew claimed that Victoria's Secret infringed on the bra she invented and protected with a utility patent.