Holy Willie, type involved with choir (9)
I believe the answer is:
hypocrite
'holy willie' is the definition.
(thesaurus)
'type involved with choir' is the wordplay.
'involved with' indicates anagramming the letters (involved can mean confusing or complex).
'type' mixed up with 'choir' makes 'HYPOCRITE'.
(Other definitions for hypocrite that I've seen before include "fraud" , "For example, Tartuffe" , "Insincere person affecting virtue" , "Dissembler" , "One who does not practise what they preach" .)