The backbone of Quark's bar is the Waiter. There were several styles of waiter costume. This Ferengi costume can be seen in many episodes of Deep Space Nine, such as 'The Maquis'. Due to the uncommon coat style and unique sleeve stripes, this costume is likely worn by a more senior Waiter.
This particular costume was worn by veteran Ferengi actor Ken Ziff. In fact, there's 'ol Ken playing tongo with Broik in the Season 2 episode 'Rules Of Acquisition'. It's hard to miss his smile.