Exploit disruptive visit of agitator (8)
I believe the answer is:
activist
'agitator' is the definition.
(thesaurus)
'exploit disruptive visit' is the wordplay.
'exploit' becomes 'act' (I've seen this before).
'disruptive' indicates an anagram.
'visit' is an anagram of 'ivist'.
'act'+'ivist'='ACTIVIST'
'of' acts as a link.
(Other definitions for activist that I've seen before include "Advocate for action" , "Vigorous political campaigner" , "One who works energetically as in politics" , "Militant" , "Cause promoter" .)