Try and swing the club a little more up and down, trying to pinch the ball off the hard fairways. That should produce a lower than normal ball flight but also enough spin to hold the green. Good luck with the shot. If you have any problems go see one of the PGA professionals in Amarillo. However, I worry that he overswings , especially under pressure, or when he tries to kill it.
Golf is a game of never ending continual learning process.
No, I would not worry that your 13 year old son has a tendency to overswing under pressure. Consider that normal. There is a young man by the name of Tiger Woods that used to overswing in his early years that through coaching and experience is continuing to learn to control his swing in pressure situations. Continue to encourage your son to have fun playing golf and provide him the coaching he needs. In San Antonio there are a great number of PGA professionals with a wealth of knowledge on the golf swing and experiences in playing the game that can help your son as he matures in his golf.