It's labeled as an "Accessory" in-game, correct? Even so, it shouldn't redirect to the Clothing article, it should redirect to the Mario & Luigi: Bowser's Inside Story version of it.
I really don't know whether I should call the article "Accessory (Horse Racing)" or "List of horse accessories in Mario Sports Superstars". I prefer the first one mostly because it's not as much as a mouthful and second we do have articles like "Sticker (Super Smash Bros. Brawl)" and not "List of stickers in Super Smash Bros. Brawl". I do suppose that "Sticker" is a "named" object in Super Smash Bros. Brawl while "accessory" in Mario Sports Superstars is referred to as lowercase so there's also a reason to name it "List of horse accessories in Mario Sports Superstars" but I'm very conflicted over the article name, still.