"Transgressing" covers it (3)
I believe the answer is:
sin
'it' is the definition.
The definition suggests a singular noun which matches the answer.
'transgressing covers' is the wordplay.
'covers' says the answer is hidden in the clue (I've seen 'covered' mean this (the answer is covered up by the clue)).
'SIN' is hidden in the letters of 'transgressing'.
Can you help me to learn more?
(Other definitions for sin that I've seen before include "Misdeed" , "Breach of moral code" , "Wicked deed" , "Depravity" , "Pride, say" .)