Delay and contain a 2v1. Slow the carrier without committing, protect the most dangerous space, and jockey across to force the attack backward or wide rather than through.
Two attackers attack a small goal or line defended by one defender. The defender must delay: backpedal to slow the ball, stay on the goal side, and do not dive in. Show the carrier away from the goal, then jockey across to block the through pass and force the ball backward. Reward the defender for delaying and forcing a backward pass. Add a recovering defender as a progression.
A lone defender facing two attackers cannot win the ball without losing the duel, and telling him so is the most useful thing a coach can do. Every attempt to intercept the pass leaves the carrier free. Every attempt to tackle the carrier leaves the pass on. The arithmetic does not allow a solution, which means the objective has to change: he is buying time for a teammate to arrive, and nothing else.
Once that is accepted, the behaviour becomes clear. Retreat while staying goal-side, keep both attackers in front, and slow the whole thing down. A 2v1 that takes six seconds to reach the box has usually become a 2v2, and the defender who achieved that has defended it perfectly without touching the ball.
Body angle does the work. Positioning slightly towards the carrier while keeping the second attacker in peripheral vision forces the attack away from the centre, and central is where the highest-value chances come from. Showing them wide costs nothing, since the wide route is longer and the finishing angle worse.
The one moment to commit is when the pass is finally forced and is under-hit or square. Before that, stepping in is a guess.
This drill is the mirror of the 2v1 attacking exercise, and running them in the same session is worth doing. Attackers who have defended a 2v1 stop passing early, because they have felt how much a premature pass helps the defender.
Save it to your private drills, then change the animation, adjust positions, swap equipment, or drop it into a session block. Or start from a blank pitch and build your own.