Possible Clues:

• Substitute performer
• Dan isn't prepared to become a locum
• Wrong about function taken by daughter substitute
• It could be night-watchman is stumped and given not out
• Stunt double, for one
• With 55-Across, be punished at school, old-style ... and a hint to this puzzle's circled letters
• Deputy who evidently doesn't stand out
• Relief when fools get sent back and put inside
• Dan isn't prepared to become a locum
• Just a substitute - and in a lousy little turn