Absorbed in thought about can having no alcohol (9)
I believe the answer is:
abstinent
'no alcohol' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'absorbed in thought about can' is the wordplay.
'absorbed in' indicates putting letters inside.
'thought about' becomes 'absent' (I can't explain this - if you can you should believe this answer much more).
'can' becomes 'tin' (both are metal containers).
'absent' enclosing 'tin' is 'ABSTINENT'.
'having' is the link.
Can you help me to learn more?
(Other definitions for abstinent that I've seen before include "Self-denying" , "Refraining from drinking alcohol" , "Restrained" , "nowhere near the drink" , "Going without, especially food and alcohol" .)