Politician involved in treason (7)
I believe the answer is:
senator
'politician involved in treason' is the definition.
(I've seen this before)
'involved in treason' is the wordplay.
'involved in' is an anagram indicator (involved can mean complex or confusing).
'treason' with letters rearranged gives 'SENATOR'.
(Other definitions for senator that I've seen before include "Member of a governing body" , "Member of Upper House engaged in treason" , "eg Bob Dole" , "US politician" , "Legislator -- treason (anag)" .)