Yes, this Don can be tricky -- it's not fair! (10)
I believe the answer is:
dishonesty
'it's not fair' is the definition.
'yes this don can be tricky' is the wordplay.
'can be tricky' indicates an anagram.
'yes'+'this'+'don'='yesthisdon'
'yesthisdon' is an anagram of 'DISHONESTY'.
(Other definitions for dishonesty that I've seen before include "Bad behaviour" , "Untrustworthiness, insincerity" , "fraud" , "Crookedness" , "Graft" .)