yes it will upset your clarki, but not for long if you have plenty of other places like cracks, crevices, or euphyllia type corals for it to host. One other thing to consider though is the fish density of your tank. if your density is high, the clarki will likely displace the territorial c;aim of at least one of your other fish. All in all if your clarki is substantially larger than any of your other fish, it isn't likely that you will have too much in the way of aggresion while it establishes it's new home.