His destination airport had a runway closed. The advertised approach that he was supposed to be flying was an approach to the closed runway, with a circle to the active runway. Thats how Id been clearing him. The way things were going, I was taking no chances. I verified on-frequency that he was aware of the runway closure and that he was supposed to circle to the other runway. It seemed to get across, although I cant say for certain if he knew about it before I spoke up.