Political movement a doctor welcomes in confidence (6)
I believe the answer is:
aplomb
'confidence' is the definition.
(thesaurus)
'political movement a doctor welcomes' is the wordplay.
'political movement' becomes 'plo' (Palestinian Liberation Organization).
'doctor' becomes 'mb' (Bachelor of Medicine, Medicinae Baccalaureus).
'welcomes' means one lot of letters goes inside another.
'a'+'mb'='amb'
'plo' placed inside 'amb' is 'APLOMB'.
'in' acts as a link.
(Other definitions for aplomb that I've seen before include "Self-satisfied dignity and confidence" , "Cool self-assurance" , "Self-possession, assurance" , "Self-satisfied assurance" , "Self confidence" .)