Cons' miry, dirty, dodgy practice? (8)
I believe the answer is:
cronyism
'dodgy practice?' is the definition.
(unethical political practice)
'cons' miry dirty' is the wordplay.
'dirty' indicates anagramming the letters.
'cons'+'miry'='consmiry'
'consmiry' with letters rearranged gives 'CRONYISM'.
(Other definitions for cronyism that I've seen before include "old boy network" , "Appointment of friends to jobs, regardless of qualifications" , "Dubious appointments" , "Favouritism shown to friends and associates" , "The appointing of personal friends to jobs" .)