Possible Clues:

• I have to follow law in force
• Sprightly gran gets out of vintage car
• Opposite of passive
• Sporty type is up and running
• Fourth session of play with England's opener having an effect?
• To perform on stage, I have to be brisk
• Voice -- it returns in cave eerily
• Part of play I have shortened, being busy
• Lively deliveries essentially following start of play
• On full-time duty