Injustice displayed by brunette? (10)
I believe the answer is:
unfairness
'injustice' is the definition.
('unfairness' can be a synonym of 'injustice')
I don't understand how the rest of the clue works.
(Other definitions for unfairness that I've seen before include "Inequity" , "Discrimination" , "quality of a brunette might you say?" .)