You can find two tied Raiders behind the counter with the security door. You can open it with the Advanced terminal nearby. Behind the door is an Expert wall safe as well. The area has two cooking stations, one near the double door and in the kitchen.
Open the double door and eliminate all the raiders in the arena. Once done, talk to Tommy and Cait. You can recruit Cait here as a new companion if agreed to bring her along.
Don't forget to find and collect an issue of Picket Fences on the table in front of the stage and the bar.