Star Trek: Deep Space Nine S02 E07 Rules of Acquisition

"At the edge of the Final Frontier, the Universe's greatest mystery is about to unfold."

Stardate: Unknown. A female Ferengi, posing as a male to be available to participate in business (a rule STRICTLY forbidden by the Ferengi government), falls for Quark during very important negotiations between the Ferengi and a Gamma Quadrant race.