Standard symbol of love mostly for upstart (7)
I believe the answer is:
parvenu
'for upstart' is the definition.
(synonyms)
'standard symbol of love mostly' is the wordplay.
'standard' becomes 'par' (standard of play in golf).
'symbol of love' becomes 'Venus' (Venus was the Roman goddess of love).
'mostly' means to remove the last letter (most but not all of the word).
'venus' with its final letter removed is 'venu'.
'par'+'venu'='PARVENU'
(Other definitions for parvenu that I've seen before include "One who climbs" , "Newly rich person" , "An upstart, new arrival to society" , "Newcomer" , "One coming" .)