Cooldown effect for a sprite

Hi all, What I need is i have a slot for an object which after placed on something, it has a recharge time say 10 seconds. I need a transparent grayed out effect which moves from left to right.. basically similar effect of a spell cooldown but not circular. Ok, I know about alpha cutoff using cutout shader on a quad.But that works for opaque objects. I need a transparent sprite cut off. I know thats not possible using alpha cut off. But how will I achieve this for a sprite renderer? Thanks for the help :)