Resentment of some unfair excesses (3)
I believe the answer is:
ire
'resentment' is the definition.
(thesaurus)
'some unfair excesses' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'IRE' can be found hidden inside 'unfair excesses'.
'of' acts as a link.
(Other definitions for ire that I've seen before include "Intense anger" , "Losing head" , "passionate feeling" , "'Anger, wrath (3)'" , "Fury" .)