A golf training apparatus to be worn on the arm of a player, for improving the player's swing by supporting his one (target directed) arm and thereby avoiding the tendency for inadvertent bending thereof during his swing. An elongate support member is clamped in position on the arm, and an adjustable loop on the apparatus is tighten-able by the player's free hand, to hold the elbow against bending. The advantage is improved accuracy of the club head, and minimization of undesirable slices or hooks. One hand operation is facilitated, to install or remove the accessory.