### Clue: King's daughter returns to harass the royal (5)
### Answer: REGAN 
 ### Explanation: Definition: King's daughter
 **Reversal of**(returns) [ NAG(to harass/to keep on at someone) + ER(abbrev. for "Elizabeth Regina", Queen Elizabeth, head of the British royals) ].
Defn: One of the daughters of Shakespeare's King Lear.