One for the road? This may stop me indulging (8)
I believe the answer is:
superego
'one for the road? this' is the definition.
The definition suggests a singular noun which matches the answer.
'stop me indulging' is the wordplay.
I cannot really understand how this works, but
'stop' could be 'go' (going is a kind of stopping) and 'go' is located in the answer.
This explanation may well be incorrect...
'may' acts as a link.
Can you help me to learn more?
(Other definitions for superego that I've seen before include "self-criticism?" , "Part of the unconscious mind - pose urge (anag)" , "Part of mind acting as conscience" , "Conscience, perhaps" , "Internal monitor of psyche" .)