There is a capx is in that link I posted above.
But you'll need to experiment with effects and blend modes to make it work like on your screenshot.
If you don't need this cone of light to be blocked by obstacles (walls, trees), then you can remove the ShadowLight object and it all can be done much easier:
create a new layer, set black color, opacity=60, transparent=no.
create a white sprite (triangle) on this layer.
apply an effect to the layer, for example Multiply.