We went to the hardware store and bought 2 large hooks that screw into the wall (in our case, solid log on one side, and a solid wood railing on the other). Then bought two pulleys that have holes on one side. They get put on the hooks, and the line strung between the pulleys, using a line tightener to keep it tight. Voila, a pulley-driven clothesline. In our case, we hung it high - our cabin has an open ceiling and loft. So the clothesline goes from the upstairs loft to the wall across from it, across our living room at about 15 feet high. No need to retract. But you might want to consider retractable. We did use one of those outside years ago and it worked great.
Since it's summer, I now hang outside, and am thinking about hanging our Tibetan peace flags on the indoor clothesline.

Then again, it sometimes rains!