Note from me to the doctor (4)
I believe the answer is:
memo
'note' is the definition.
(memo is a kind of note)
'me to the doctor' is the wordplay.
'to the doctor' becomes 'mo' (medical officer**).
'me'+'mo'='MEMO'
'from' is the link.
(Other definitions for memo that I've seen before include "diplomatic communication?" , "Short note or message" , "Office note" , "A brief record of events" , "In brief, a note of events" .)