I agree, elevator only by definition.

To further confuse matters, some designers may ensure that the other controls surfaces are also protected below Va so for some models it might be all-inclusive...but don't bet on it unless it's documented.

I suspect that the ailerons usually have a greater margin than the elevator anyway in most designs. Aileron inputs don't cause the wing load to change dramatically.

The rudder/vert stab on the other hand may well have lower margins...as was demonstrated dramatically in 2001.