Sad hack died a villain (9)
I believe the answer is:
bluebeard
'a villain' is the definition.
Both the answer and definition are singular nouns.
Maybe they are linked in a way I don't understand?
'sad hack died' is the wordplay.
'sad' becomes 'blue' (similar in meaning).
'hack' becomes 'bear' (both can mean to be able to tolerate or stand).
'died' becomes 'd' (abbreviation next to the year of someone's death).
'blue'+'bear'+'d'='BLUEBEARD'
Can you help me to learn more?
(Other definitions for bluebeard that I've seen before include "serial wife-killer" , "Fairy-tale character who murdered six wives and hid bodies in locked room" , "Villain with many wives" , "Be durable (anag) - wife-murderer" , "Serial killer" .)