Credit to Caspahh.
There are some prerequisites for this achievement first: You will need to have progressed the stories of Episodes 1, 3, 4, 5, and 7 to the point where you have free roam access to the following areas:
Kachiro on Kashyyyk
Echo Base on Hoth
Niima Outpost on Jakku
Mos Eisley, Mos Espa, and Jundland Wastes on Tatooine
Once you have access to all of these areas, make your way to the cantina in Mos Eisley. You should have been here before due to story for Episode 4, but in case you forgot, it is on the north side of the area on the very edge.
Once inside you will talk to Doctor Evazan who will be standing immediately to your right when you enter. Initiate his side quest called "No arm in asking" where you will collect various pieces for a new arm for Ponda Baba. NOTE: If you don't see them standing there at the entrance, then you most likely have not progressed one or more of the stories far enough.
Once completing his whole quest, return to the cantina and speak to Ponda Baba, the other guy standing right at the door, and start his quest. "Baba Bar Brawl" will simply have you beat up and antagonize the patrons of the cantina. Once you complete this quest, we are now ready to go for the achievement.
Remain in the cantina and switch to any force user, if you weren't already playing as one. There will be two tables on either side of the cantina with five goons at each one. Walk up to either table and use the Jedi Mind Trick "Panic" to make them start shooting each other. You will need to be quick about this as you need to do this on a few of them before too many of them kill each other.