I figured that one out. Just Crucible. (Destiny)

by bluerunner , Music City, Thursday, October 29, 2015, 09:18 (3409 days ago) @ BeardFade

You just have to get 7 headshot kills during a game. It doesn't have to be a spree or on the same mag like the PvE part.

I went into clash and just followed teammates around. When they engaged somebody, I ran up and shot them in the head. As long as you hang back a little and let the opponents get focused on your teammate, you shouldn't have much trouble. Just steal your teammates' kills. Don't try to kill anybody on your own. You can't win a 1v1 fight with that crappy gun.