Family to dismiss massacre (9)
I believe the answer is:
bloodshed
'massacre' is the definition.
(I know that bloodshed is a type of massacre)
'family to dismiss' is the wordplay.
'family' becomes 'blood' (blood can mean one's family).
'to dismiss' becomes 'shed' (I can't justify this - if you can you should believe this answer much more).
'blood'+'shed'='BLOODSHED'
Can you help me to learn more?
(Other definitions for bloodshed that I've seen before include "The killing or wounding of people, very gory" , "Indiscriminate slaughter" , "Carnage" .)