why does Venus have such a high Albedo

Answer 1

Because its dense clouds scatter about 80% of the light received..

Answer 2

Correct. It is because of the clouds. They are made of low-absorbing liquid droplets -- mostly sulfuric acid. They are a bit more absorbing that earth's water clouds, but still have a high albedo.

Light that enters a dense nonabsorbing cloud is scattered back before most of it can penetrate through the cloud.