Mystery writer Grafton (3)
I believe the answer is:
sue
'mystery writer grafton' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sue that I've seen before include "Institute legal proceedings (against someone)" , "Bring charges against - girl" , "take to 10 [COURT] !" , "Prosecute; girl's name" , "The girl to take to court" .)