Roll has no secondary effect, it is the motion the aircraft performs when it rotates about its longitudinal axis, whatever may cause that roll.
I think that's going a bit far. There are other-axis effects for not only controls that are designed to rotate the aircraft around an axis, but also rotation about the axis itself. Roll causes both roll-damping (which tends to oppose the roll couple from the ailerons) and some yaw. The latter effect is small, because it is secondary.