Male ego of Scot confronting his doctor (8)
I believe the answer is:
machismo
'male ego' is the definition.
'scot confronting his doctor' is the wordplay.
'scot' becomes 'mac' (many Scottish surnames begin with Mac).
'confronting' means one lot of letters go next to another.
'doctor' becomes 'mo' (medical officer**).
'mac'+'his'+'mo'='MACHISMO'
'of' acts as a link.
(Other definitions for machismo that I've seen before include "A show of virility or manliness" , "Cult of masculinity" , "Cult of virility" , "Expression of male pride" , "large injection of testosterone!" .)