One who throws out voter has Liberal turning to judge (7)
I believe the answer is:
ejector
'one who throws out' is the definition.
(someone who ejects or throws others out)
'voter has liberal turning to judge' is the wordplay.
I cannot really understand how this works, but
'to' is found in the answer.
'judge' could be 'j' (abbreviation for judge) and 'j' is found in the answer.
This explanation may well be incorrect...
(Other definitions for ejector that I've seen before include "One leaving plane in an emergency" , "A bouncer" , "Thrower-out" , "Someone supplanting another" , "Mechanism for getting rid of empty shell cases after firing" .)