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