Online Achievement
Objective of the achievement is to 'Neutralize' i.e kill, an online player who is hunting you.
To start you need to open up your in-game phone with
and choose 'Multiplayer' from that screen choose 'Bounty Hunter' then 'Trigger a Bounty'
Matchmaking will then begin and once players have been found, you will be given a 3 star wanted level and one or more PvP pursuers will be after you.
Run them over, gun them down, kill them in anyway you can and the achievement will pop instantly
Good luck
*Edit* CraziestSock adds that if you're unable to find a match, resetting the game and searching straight away should help