Single men barred from orgy, catching flogger's interest in passing (9)
I believe the answer is:
scatology
'single' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Perhaps you can see a link between them that I can't see?
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for scatology that I've seen before include "Excessive interest in obscene things" , "dropping science" .)