Owner favouring voting system that's to run (10)
I believe the answer is:
proprietor
'owner' is the definition.
(I've seen this before)
'favouring voting system that's to run' is the wordplay.
'favouring' becomes 'pro' (I've seen this in other clues).
'voting system' becomes 'pr' (I've seen this in other clues).
'that's' becomes 'ie'.
'run' becomes 'r' (cricket abbreviation).
'pro'+'pr'+'ie'+'to'+'r'='PROPRIETOR'
(Other definitions for proprietor that I've seen before include "Business owner" , "Landlord" .)