In a medium saucepan, bring the water to a boil with the butter and a generous pinch of salt. Stir in the couscous, cover and remove from the heat.
In a large deep skillet, heat 1/4 cup of the olive oil until shimmering. Add the garlic and cook over high heat, stirring, until lightly browned, about 1 minute. Stir in the crushed red pepper and the wine and boil until the wine is reduced by half, about 5 minutes. Add the clams and bring to a boil. Cover the skillet, lower the heat to moderate and cook, stirring occasionally, until the clams open, about 3 minutes. Add the red peppers, beans and scallions and cook just until heated through, about 1 minute.
Fluff the couscous with a fork and spoon it into 4 deep bowls. Spoon the clams, peppers and beans over the couscous. Stir the remaining 1 tablespoon of olive oil into the broth, spoon it over the clams and serve.