Last Stuart monarch (4)
I believe the answer is:
anne
'last stuart monarch' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for anne that I've seen before include "Name of queen or princess" , "18th century Queen" , "Boleyn or Hathaway, say" , "First name of two of Henry VIII's wives" , "One of two Henry VIII wives" .)