This video guides you through the process on how to export clothing separate to a character so that you can apply it to a naked character base in Unreal Engine. I use CC3 and Maya, so I basically get the clothing rigged from CC3 and manage to import the clothing on its own into unreal so that I can attach it to a character base.
If you don't use CC3, you can pretty much follow the steps from Maya if the clothing is rigged and skinned to a skeleton. This would be a great method if you want to create an RPG game like Dark Souls, Skyrim, GTA or any game that lets you equip different pieces of clothing to a character.
Let me know if this helps.