One quiet look by doctor gives confidence (6)
I believe the answer is:
aplomb
'confidence' is the definition.
(thesaurus)
'one quiet look by doctor' is the wordplay.
'one' becomes 'a'.
'quiet' becomes 'p' (music symbol for 'piano').
'look' becomes 'lo'.
'by' says to put letters next to each other.
'doctor' becomes 'mb' (Bachelor of Medicine, Medicinae Baccalaureus**).
'a'+'p'+'lo'+'mb'='APLOMB'
'gives' is the link.
(Other definitions for aplomb that I've seen before include "Self-satisfied assurance" , "Cool self-assurance" , "Dignified self-confidence" , "Air of self-satisfied confidence" , "coolness is required" .)