On episode 14 - YE$, at 6:21 in this episode, we see the crew being debriefed by Aramaki. The chief remarks that she is wearing "some get-up", inquiring whether she is searching for a specific kind of attention. She replies, somewhat... despairingly(?), with "...; I just... don't have a choice."
The scene prior to this ended with her being ejected from a building through a window and landing on a pile of trash. She is noticeably soiled by "garbage-type fluids" and, presumably, needs to get cleaned up.
It is not explicit, but it seems that only a few hours, at most, have passed between the incident and the debriefing.
Aside from being her usual hot-gun-toting-super-hacker-ninja self, I have missed the implication as to why this particular outfit is "mandatory". Is there a specific clue I missed or was it just to imply that she may have had other, personal, obligations for which she was still dressed? Her outfit was definitely extreme for being at "the office", even for her.