Voter is volatile, it's obvious (5)
I believe the answer is:
overt
'obvious' is the definition.
('overt' can be similar in meaning to 'obvious')
'voter is volatile' is the wordplay.
'is volatile' indicates an anagram.
'voter' with letters rearranged gives 'OVERT'.
'it's' is the link.
(Other definitions for overt that I've seen before include "not disguised" , "Done in an obvious way" , "Plain to see - manifest" , "Not locked away" , "Open, not 1 across" .)