Good Parisian, upwardly mobile bigwig (3)
I believe the answer is:
nob
'bigwig' is the definition.
(both can mean a wealthy person)
'good parisian upwardly mobile' is the wordplay.
'good parisian' becomes 'bon' ('good' in French).
'upwardly mobile' says the letters should be written in reverse.
'bon' written backwards gives 'NOB'.
(Other definitions for nob that I've seen before include "Aristocrat" , "Person of wealth or high social position" , "A slangy person of high rank - c'est bon" , "A posh gent - c'est bon" , "Jack" .)