Make it a nuclear powered twilight planet
If the heat doesn't come from the star, it has to come from somewhere. Why not the planet itself?
Let's assume the following:
This is a roughly Earth like planet. Same size, same atmosphere, same orbit.
It orbits a dim star, red dwarf or some such. This star has very high metalicity, indicating an advanced age of the surrounding stellar neighborhood.
Due to the high metalicity of the solar system, there is an unusually high quantity of uranium in the core and mantle of this planet.
Due to Decay Heat, the uranium will heat up. If this decay heat is high enough, it will heat the crust sufficient to replace the heat that would have come from the Sun on Earth.
Decay Heat decreases with time so either handwaving or careful calculation will be required to figure out how much uranium it will take to keep the planet warm and how long it will be able to do so.
Interesting to note that about half of Earth's heat come from Decay Heat. In this twilight world, maybe 75% or 90% of the planets heat comes from decay heat.
Heating this way should give you the clear skies and warm weather you want while keeping a dim sun.