Headstone heading (3)
I believe the answer is:
rip
'headstone heading' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for rip that I've seen before include "Louche character" , "Letters often seen on gravestone" , "The familiar Mr Van Winkle" , "Tear violently" , "Rest in peace" .)