Upstart from Standard snubbed Evening Star (7)
I believe the answer is:
parvenu
'upstart' is the definition.
(synonyms)
'standard snubbed evening star' is the wordplay.
'standard' becomes 'par' (standard of play in golf).
'snubbed' means to remove the last letter (could historically mean cutting the end off).
'evening star' becomes 'venus' (I've seen this in another clue).
'venus' with its last letter taken away is 'venu'.
'par'+'venu'='PARVENU'
'from' acts as a link.
(Other definitions for parvenu that I've seen before include "Arriviste" , "Social climber" , "Newly rich person" , "Newcomer" , "One who climbs" .)