Topped shots result when a player’s swing radius shortens through impact. This can happen several ways, but most common is over-bending of the arms. To remedy this, two easy drills:
1) Place a tee in the ground a few inches in front of the ball being hit. Make sure the tee is level with the turf. Try to hit both the ball and tee when swinging.
2) Make some half swings where you hold a half-finish position. Assure both arms are straight and body is facing the target. You’re doing it right when you hit lower-than normal trajectory shots with a slight draw.
Don’t go for distance on these swings- quality of contact is foremost.