Doctor Muriel visited, receiving one authentic look (14)
I believe the answer is:
verisimilitude
'authentic look' is the definition.
'doctor muriel visited receiving one' is the wordplay.
'doctor' is an anagram indicator.
'receiving' is an insertion indicator.
'one' becomes 'i' (Roman numeral).
'muriel'+'visited'='murielvisited'
'murielvisited' with letters rearranged gives 'verisimiltude'.
'verisimiltude' placed around 'i' is 'VERISIMILITUDE'.
(Other definitions for verisimilitude that I've seen before include "semblance of truth" , "apparent reality" , "Appearance of being true" .)