Really need to see a picture of it to make an ID, which will go a long way towards being able to say if I think the Clarkii will be hosted by it, and if it will be okay.
When I first introduce my new Saddleback pair to my tank, they went right for my Haddoni, both of them got a little bit stuck, but within 20 minutes had adjusted to it, and have been fine every since.