When rotating an arrow (as pointer on a dial) how do I move the pivot point?

because rotate works from the center of the object, arrow object, I presume in this case. I would make the arrow twice as long, use advanced gradient fill to have it filled only half way. then add the rotate effect.

Draw a small box. Set it to no fill and no outline. Position it on the base end of the arrow - about as far out as the arrow head. Group the arrow and the box, then add the animation. You have now moved the center pivot point to the middle of the grouped objects / the base of the arrow. If it isn't quite right, double click to select just the box while maintaining the group and move the box around to get it right.