Unseat when simultaneous translation's revealed (4)
I believe the answer is:
oust
'unseat' is the definition.
(I know that unseat can be written as oust)
'when simultaneous translation's revealed' is the wordplay.
'revealed' indicates the answer is hidden within the clue (I've seen 'revealing' mean this).
'OUST' is hidden within 'when simultaneous translations'.
(Other definitions for oust that I've seen before include "Evict" , "kick out" , "Turf out" , "Depose" , "Turn out" .)