Who's a handsome young man? A university teacher (6)
I believe the answer is:
adonis
'who's a handsome young' is the definition.
I know that 'handsome' relates to this answer.
'man? a university teacher' is the wordplay.
'man?' becomes 'Ado'.
'a university teacher' becomes 'nis' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'ado'+'nis'='ADONIS'
Can you help me to learn more?
(Other definitions for adonis that I've seen before include "Extremely handsome young man" , "A very handsome legendary Greek" , "Archetype of male beauty" , "Legendary lover" , "Beautiful young man" .)