The Outer Worlds Slaughterhouse Clive quest involves making your way to the last remaining boarst factory on Monarch and dealing with Clive Lumbergh, the self-proclaimed "Boarst King". You can find the Slaughterhouse Clive quest in The Outer Worlds by speaking to Catherine Malin in Fallbrook, because she wants Lumbergh out of the way. Here's how to get into the C&P Boarst Factory and deal with Clive Lumbergh.
How to get into the C&P Boarst Factory
Approaching the front of the C&P Boarst Factory will present you with a number of automechanicals and guards who will shoot you if you step foot inside the restricted area. Over to the right is a sealed entrance, again guarded by two automechanicals. However, if you head left from the main entrance and down into the creek, you'll find a third, unguarded entrance.
Entering through here will lead you to a ladder beneath the cystypig trough, but again, the rest of the facility is a restricted area. So how do you get the Boarst Factory ID Catridge so you can get disguised while inside?
Head back to Fallbrook and seek out Duncan Elley, the shopkeeper in the SubLight Dry Goods & Sundry store. You can buy the Boarst Factory ID Cartridge off him, which will allow you to enter the C&P Boarst Factory undetected. Sneak your way to the quest marker at the back of the factory where you'll find Clive Lumbergh, or opt for a method of sabotaging the factory.
Speaking with Clive presents you with a few options; you can kill him like Catherine ordered, you can go back and kill Catherine like Clive wants you to do, or you can try and get the two to work together. Of course, that's the preferential option because you're not a stone cold killer (ignore this if you are, in fact, a stone cold killer), but you'll need high enough speech stats in order to manage it. Good luck!