I think he intended to get under it and play it with his head, but misjudged the flight or spin of the ball and was left with no option but to stab at it with his leg. I don't know, that's just how it looked to me at the game.
Sorry, I feel like you're just searching for a way to say it was not not a poor decision, but rather it was him making the best possible decision after bad luck putting him in a difficult position. Even if we accept the idea that he was off balance, it was still a poor decision. He was far enough out, he could have just let the ball bounce as he regained his balance, shielded the forward off the next time it came down, and either headed it back to the keeper, or played it out of bounds, or he could have tried . Instead he chose to try to make a difficult kick while off balance, where if he missed, then he would be out of the play, with no chance at the ball. But to be honest, in looking at the replay, he only looks like he's off balance after he attempts his difficult clearance and misses the ball completely, meaning the difficult clearance that he tried to do, but failed, is what put him off balance, and allowed the opponent to get around him and get to the ball. He should have just run onto it, brought it down and played the keeper or played it out. A young player making a poor decision that leads to a goal, while unfortunate, isn't some awful crime, it's actually kind of expected, and people understand that. Nobody is killing him for it, he just needs to learn from it and use it to help himself grow as a player.