Monument to doctor (4)
I believe the answer is:
tomb
'monument' is the definition.
(I have seen 'Sepulchral monument ' mean 'tomb' so perhaps 'monument' could also mean 'tomb')
'to doctor' is the wordplay.
'doctor' becomes 'mb' (Bachelor of Medicine, Medicinae Baccalaureus**).
'to'+'mb'='TOMB'
(Other definitions for tomb that I've seen before include "Burial chamber" , "Burial-vault" , "Place of burial, grave or vault" , "grave situation" , "Large vault" .)