A ballot on old deity (6)
I believe the answer is:
apollo
'deity' is the definition.
(Apollo is an example)
'a ballot on old' is the wordplay.
'ballot' becomes 'poll' (I've seen this before).
'on' means one lot of letters go next to another.
'old' becomes 'o' (abbreviation as in OT - Old Testament).
'a'+'poll'+'o'='APOLLO'
(Other definitions for apollo that I've seen before include "mission of high-flying Americans?" , "God of light and US space programme" , "Greek god - US space programme dedicated to moon landings - butterfly" , "Deity" , "Greek god of the sun (6)" .)