MP in election unusually short (10)
I believe the answer is:
incomplete
'short' is the definition.
(thesaurus)
'mp in election unusually' is the wordplay.
'in' is an insertion indicator.
'unusually' is an anagram indicator.
'election' is an anagram of 'incolete'.
'mp' put within 'incolete' is 'INCOMPLETE'.
(Other definitions for incomplete that I've seen before include "Not whole" , "Lacking" , "not sufficient" , "Not yet finished" , "Unfinished" .)