System of voting (6)
I believe the answer is:
ballot
'system of voting' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for ballot that I've seen before include "Lottery (eg, for tickets)" , "Voting procedure" , "Plebiscite" , "System of voting secretly" , "Lottery to allocate (tickets) among applicants" .)