THE PIC STATED HE HAD JUST TAKEN OFF FROM THE AIRPORT AND MADE A STEEP BANKED TURN TO THE LEFT. HE SAID THE ATTITUDE OF THE AIRPLANE IN THE TURN WAS SUCH THAT THE 'WING STALLED CAUSING THE PLANE TO ENTER A LEFT SPIN.' THE AIRPLANE IMPACTED THE GROUND AND THE PIC SUSTAINED MINOR INJURIES AND THE AIRCRAFT WAS SUBSTANTIALLY DAMAGED.