Arriviste ruffled up raven (7)
I believe the answer is:
parvenu
'arriviste' is the definition.
(I know that arriviste can be written as parvenu)
'ruffled up raven' is the wordplay.
'ruffled' indicates anagramming the letters.
'up'+'raven'='upraven'
'upraven' with letters rearranged gives 'PARVENU'.
(Other definitions for parvenu that I've seen before include "An upstart, new arrival to society" , "One coming" , "One who climbs" , "Nouveau riche" , "Newcomer" .)