Time to interrupt gullible citizen (6)
I believe the answer is:
native
'citizen' is the definition.
(thesaurus)
'time to interrupt gullible' is the wordplay.
'time' becomes 't'.
'to interrupt' is an insertion indicator.
'gullible' becomes 'naive' ('naive' can be similar in meaning to 'gullible').
't' put inside 'naive' is 'NATIVE'.
(Other definitions for native that I've seen before include "One who belongs to place by birth" , "Local inhabitant" , "Indigenous person" , "Endemic - aborigine" , "Belonging to one by birth" .)