Won't he be found out? (7)
I believe the answer is:
insider
'won't he be found out?' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'won't he' is the wordplay.
I cannot quite see how this works, but
'he' could be 'sid' and 'sid' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for insider that I've seen before include "Accepted member of group - may be privy to scarce information" , "I may know secrets" , "Member of a specific group" , "One of us" , "member of the club" .)