Hi,
Very easy chevo. The way I got it was to select solo, arena and stack the odds in your favor by adjusting the settings to start at stage 3. I picked Avery as its a small map. Just go to town on the hunters and when on to the last one just press "b" and sneak attack them. You can do it mid battle as long as you sneak and attack you will get the chevo if it's the final kill. You don't need to run and hide, I went into sneak mode directly in front of the hunter and got it no worries.
Thanks for reading!