Clara (クレア) is a member of the USNAStardust who goes by "Hunter Q".
Clara and Rachel were sent to capture or kill Charles Sullivan code named "Demus Second" who was a fugitive. They initially had split up from Angie Sirius as they had spotted another person along with Charles Sullivan hence forming two teams. They ended up helping track him down and wound him to the point where Angie Sirius was able to shoot a bullet reinforced with Data Fortification to pierce through his defenses, destroying his heart. 
The name "Hunter Q" refers to Q being the 17th Latin character.