Possible Clues:

• Substitute scepter-wielder
• Ruler appointed when monarch is too young or away
• What's concerning man who substitutes for ruler?
• University V.I.P.
• Regular payment to retain, say, acting chief
• One who acts for a monarch
• There's little sleep to be had here
• Person who rules for a sovereign
• That's about a gentleman for a monarch
• Person appointed to rule because monarch is too young