I could be wrong about this but as far as I know there is nothing that can be done about this unless it is reported to an admin or moderator ingame, meaning the player will not be punished for using your tag unless they refuse to remove it when asked by a member of staff.
It is still good that you have reported this matter here though, as any staff reading your report will know to ask the player to remove the clan tag, or kick them from the game until they do so. If the problem persists then further action may be taken.
