Original voting system, first popular with electorate, primarily (8)
I believe the answer is:
pristine
'original' is the definition.
(I've seen this before)
'voting system first popular with electorate primarily' is the wordplay.
'voting system' becomes 'PR' (proportional representation).
'first' becomes 'ist' (ist resembles 1st).
'popular' becomes 'in' ('in' can mean trendy).
'with' means one lot of letters go next to another.
'primarily' indicates taking the first letters.
The first letter of 'electorate' is 'e'.
'pr'+'ist'+'in'+'e'='PRISTINE'
(Other definitions for pristine that I've seen before include "Immaculate" , "Spotless" , "not spoiled" , "Fresh and clean as if new" , "maiden voyage?" .)