Unpleasant matter hidden by being ungentlemanly (5)
I believe the answer is:
gunge
'unpleasant matter' is the definition.
The definition suggests a singular noun which matches the answer.
'hidden by being ungentlemanly' is the wordplay.
'hidden' says the answer is hidden in the clue.
'GUNGE' is hidden within 'by being ungentlemanly'.
Can you help me to learn more?
(Other definitions for gunge that I've seen before include "Unpleasant sticky material" , "Nasty and sticky stuff" , "Wet sloppy stuff" , "Unpleasant sticky stuff" , "Thick sticky muck" .)