Because clowns are wired for hierarchy and dominance it is not unusual for them to focus on other fish, inverts, or even corals in addition to others of the same species. I recommend that you start with rearranging some of the aquascape or maybe adding something else to the aquascape (even if it is just temporary). There may come a time when you need to remove the clown, but I personally wouldn't make that the first option because it is quite possible that when you reintroduce the clown to the DT then she will start the dominance process all over again. Of course, if the aggression is potentially life threatening then I would remove one of the two fish immediately. I realize that this is not a pleasant process to watch, but it is part of the frustration and mystery of keeping clowns.
