A musical director, I’m involved with orchestra (11)
I believe the answer is:
choirmaster
'a musical director' is the definition.
(someone directing a musical group)
'i'm involved with orchestra' is the wordplay.
'involved with' is an anagram indicator (involved can mean confusing or complex).
'im' mixed up with 'orchestra' can make 'CHOIRMASTER'.
(Other definitions for choirmaster that I've seen before include "Singers' leader" , "Director of singers" .)