Top place is vacated in a vote (4)
I believe the answer is:
apex
'top' is the definition.
(thesaurus)
'place is vacated in a vote' is the wordplay.
'is vacated' says to hollow out the word (remove centre letters).
'in' means one lot of letters goes inside another.
'vote' becomes 'x' (how votes are marked).
'place' with its middle taken out is 'pe'.
'a'+'x'='ax'
'pe' inserted into 'ax' is 'APEX'.
(Other definitions for apex that I've seen before include "Cheap fare" , "Summit - pinnacle" , "Acme" , "high-point" , "Uppermost point" .)