Made great efforts to get voters out (6)
I believe the answer is:
strove
'made great efforts' is the definition.
(I've seen this before)
'voters out' is the wordplay.
'out' is an anagram indicator (out can mean wrong or inaccurate).
'voters' with letters rearranged gives 'STROVE'.
'to get' is the link.
(Other definitions for strove that I've seen before include "Made great efforts" , "Voters (anag) - made every effort" , "Struggled" , "Tried hard for voters" , "Endeavoured" .)