Changing line electing wit (12)
I believe the answer is:
intelligence
'wit' is the definition.
(thesaurus)
'changing line electing' is the wordplay.
'changing' is an anagram indicator.
'line'+'electing'='lineelecting'
'lineelecting' is an anagram of 'INTELLIGENCE'.
(Other definitions for intelligence that I've seen before include "Brains -- news" , "Information from spies" , "Ken" , "Military information" , "Dope" .)