Stranger is taking nothing back about the doctor (5)
I believe the answer is:
odder
'stranger' is the definition.
(I've seen this before)
'nothing back about the doctor' is the wordplay.
'nothing' becomes 'O' (looks like zero - 0).
'back' is a reversal indicator.
'about' becomes 're' (common abbreviation for 'with reference to').
'the doctor' becomes 'dd' (Doctor of Divinity).
're'+'dd'='redd'
'redd' written backwards gives 'dder'.
'o'+'dder'='ODDER'
'is taking' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for odder that I've seen before include "More strange or less even" , "more rum" , "More unusual" , "Stranger" , "More peculiar" .)