Defector has a position at top Electorate (8)
I believe the answer is:
apostate
'defector' is the definition.
(I've seen this before)
'a position at top electorate' is the wordplay.
'position' becomes 'post' (synonyms).
'top' says to take the initial letters (in a down clue, the first letter is top).
The initial letter of 'electorate' is 'e'.
'a'+'post'+'at'+'e'='APOSTATE'
'has' acts as a link.
(Other definitions for apostate that I've seen before include "Person who renounces a former belief or religion" , "Deserte" , "One deserting" , "Renouncer of a belief" , "heretic" .)