The RadRating does not expose an event that fits your requirements. Perhaps you can use the MouseLeftButtonUp event as this is what the control uses internally to detect the user click. Another solution could be to use the ValueChanged event and see if the mouse is over a RadRatingItem element (use Mouse.DirectlyOver static property).
If you need more information I will ask that you provide more details about your scenario, including why you need such functionality. Then we may be able to suggest an even better approach for this.
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