Professor (3)
'professor' is the definition.
(term for a university professor)
This is all the clue.
(Other definitions for don that I've seen before include "Put on or assume" , "Mafia chief or Spanish title" , "Yorkshire river" , "European river" , "Put on the learned man" .)
'professor' is the definition.
(thesaurus)
This is all the clue.
(Other definitions for emeritus that I've seen before include "Rue items that describe person retired but retaining title" , "Use remit for retained title of retired professional" , "Retired and retaining title, say professor" , "Keeping rank, retired" , "Honorary title" .)