Blood feud (8)
I believe the answer is:
vendetta
'blood feud' is the definition.
(I know that blood feud can be written as vendetta)
This is the entire clue.
(Other definitions for vendetta that I've seen before include "intense feud" , "Violent feud" , "Long-running quarrel" , "ongoing row" , "A prolonged feud, associated with Sicily" .)