Secret society member fed owl old nuts (9)
I believe the answer is:
oddfellow
'secret society member' is the definition.
'oddfellow' can be an answer for 'member' (I have seen 'Member of fraternity' mean 'oddfellow' so perhaps 'member' could also mean 'oddfellow'). I am unsure of the 'secret society' bit.
'fed owl old nuts' is the wordplay.
'nuts' is an anagram indicator (nuts can mean crazy).
'fed'+'owl'+'old'='fedowlold'
'fedowlold' anagrammed gives 'ODDFELLOW'.
Can you help me to learn more?
(Other definitions for oddfellow that I've seen before include "Member of friendly society (funny chap!)" , "Member of fraternity" , "fraternal member" , "member of secret society" , "one of a fraternity" .)