Hard, I say repeatedly, to secure voting for the rabble (3,6)
I believe the answer is:
hoi polloi
'the rabble' is the definition.
(I've seen this before)
'hard i say repeatedly to secure voting' is the wordplay.
'hard' becomes 'h' (abbreviation used in pencil classifications).
'i say' becomes 'oi' (both are expressions of shock or outrage).
'repeatedly' indicates the doubling of some letters.
'to secure' is an insertion indicator (inserted letters are secured inside).
'voting' becomes 'poll' (I've seen this in other clues).
'oi' doubled is 'oioi'.
'oioi' placed around 'poll' is 'oipolloi'.
'h'+'oipolloi'='HOI-POLLOI'
'for' acts as a link.
(Other definitions for hoi polloi that I've seen before include "The common people generally" , "Proletariat" , "The plain people in Greece" , "The common people - in Greece" , "The unwashed masses!" .)