Exaggerate spoiled vote rates (9)
I believe the answer is:
overstate
'exaggerate' is the definition.
(I know that exaggerate can be written as overstate)
'spoiled vote rates' is the wordplay.
'spoiled' is an anagram indicator.
'vote'+'rates'='voterates'
'voterates' is an anagram of 'OVERSTATE'.
(Other definitions for overstate that I've seen before include "Exaggerate, go beyond bounds of truth" , "Exaggerate, make too much of" , "lay it on thick" .)