How to clip Volume and keep rgba 4 scalar components

Dear Experts,

I want to clip my volume data which has 4 scalar components: rgba, my expected result is a portion of origin: the same color and opacity, but the real result is a solid entity which lost origin rgba information…

How can i make a volume clip, let it keep origin rgba and then show it just like it is clipped from origin?

Thanks & Regards,
Sharon