I am not exactly sure about your complaints...

if this subordinate dresses cheap/tacky, I would say there is not much you can do. Its her personal style and taste...either she has or has not. The earlier you embrace this difference, the less frustration you will have.

On the other hand, if she dresses too revealing, you need to have a formal discussion with her along with someone from HR/personnel departmemnt...documenting the issues and having a development plan in check.

Whether your clienteles are bankers or construction workers bears insignificances to this matter.