A blow for justice (5)
I believe the answer is:
right
'justice' is the definition.
(right is a kind of justice)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for right that I've seen before include "A person is entitled to it" , "Conservative - correct" , "Sound" , "Spot-on" , "Factual" .)