An arm-bar from closed guard, with a set up that takes into account the opponent trying to tuck in their arm to prevent the arm drag. Starting from closed guard, assuming the attack is done on the opponents right arm (i.e. on our left).
With your left arm grab the opponents wrist, and with the right arm reach over and across to cup the back of the triceps on the same arm. Bump with the hips to displace the arm then hip escape turning onto your right shoulder and dragging the opponents arm into the hole you’ve created. Quickly reach over the opponents back and grab under their left armpit (on your right) to keep their posture broken down. Bring the left foot up onto the hip, using your leg to also keep the arm trapped. Keeping the grip on the armpit, allow the opponents head to pop out from under your left arm, as this happens cut an angle to you can chop down high on the opponents back with your right leg. Left go of the shoulder grip with your left hand, and use it to push the opponents face away so you can bring your left leg up and chop down on the back of their neck. Keep both legs heavy! From here make sure the thumb on the trapped arm is pointing up, bridge and apply the arm-bar.