For this achievement you will need to craft the Hunter outfit out of (1) White Jaguar Skin and (1) Red Howler Monkey Skin.
The easiest method is to buy both at a Store and then go to the crafting menu (the White Jaguar Pelt is 6000R and the Red Howler Monkey is 5000R).
If you want to save your money you can find the White Jaguar at Cayman Sound (327,334). You have to complete the Templar Hunt which triggers a cut scene where you kill the Jaguar (be sure to skin the animal after the cut scene).
The Red Howler Monkey can be found at Isla Providencia (502,44). This island is unlocked through progression in the story.