One of the least elegant ideas ever is windscreen wipers for headlamps in vehicles. The idea just doesn’t scale down from windscreens very effectively (and it’s questionable how well even these work).
Today’s invention is simply a frustum-shaped shield which covers whatever lamp and lens combination is incorporated in a given car.
The transparent shield can be driven backwards and forwards or unidirectionally about an axis (the orientation of which would be a choice for the designer). As this rotation occurs, the glass surface is cleaned by a brush running down the face (which might be supplied with a small flow of water).
The rear of the frustum could be made of body-coloured metal, so that when driving during the day, or when parked, the lens unit would be protected inside.