Grave letters from a reprobate (3)
I believe the answer is:
rip
I believe this is a double definition.
'grave letters' is the first definition.
(I've seen this in another clue)
'a reprobate' is the second definition.
(informal term for a fraud)
'from' acts as a link.
(Other definitions for rip that I've seen before include "Letters on a grave stone" , "Shred" , "Tear violently" , "dissolute character" , "tide" .)