Madman involved in a cult (7)
I believe the answer is:
lunatic
'madman' is the definition.
(synonyms)
'involved in a cult' is the wordplay.
'involved' is an anagram indicator (involved can mean confusing or complex).
'in'+'a'+'cult'='inacult'
'inacult' with letters rearranged gives 'LUNATIC'.
(Other definitions for lunatic that I've seen before include "Type of fringe" , "Mad" , "Foolish person" , "Crackers or nuts" , "Deranged" .)