Some polygons in the dress got normal-reversed. It is not skin you see poking thru. It is the default background (look in the material room). This usually happens when the cloth polygons are INSIDE Stef when you start the clothify process. It is very important to make sure everything of the cloth is outside, not intersecting with the Stef figure. If you want to correct this particular dress, you will need a 3D modeller program. Poser cannot correct it.