During the Battle of Jakku Mission, you have to destroy some TIE Bombers in a hanger of a downed Imperial Star Destroyer, when you land your X-Wing, proceed to hug the right hand side of the playable area, keeping a bit of distance to ensure you don't burn to death from the wreckage. At the far end is an officer and a Scout Trooper, simply sneak behind him, click L3 when prompted and you should perform a takedown, thus earning your trophy.
See below YouTube video showing how I did it.
https://m.youtube.com/watch?v=risufstc2FE