It borders on being a bit criminal (3)
I believe the answer is:
rim
'it borders on' is the definition.
The definition suggests a singular noun which matches the answer.
'a bit criminal' is the wordplay.
'a bit' says the answer is hidden in the clue (I've seen 'bit of' mean this).
'RIM' is hidden in the letters of 'criminal'.
'being' acts as a link.
Can you help me to learn more?
(Other definitions for rim that I've seen before include "Brim, edge" , "Curved edge" , "Circular outer edge" , "Top edge" , "Edge, border" .)