Success -- the girl's almost top up to now (8)
I believe the answer is:
hitherto
'up to now' is the definition.
(thesaurus)
'success the girl's almost top' is the wordplay.
'success' becomes 'hit' (hit is a kind of success).
'the girl' becomes 'her' (**).
'almost' means to remove the last letter (most of the word but not all of it).
'top' with its last letter taken off is 'to'.
'hit'+'her'+'to'='HITHERTO'
(Other definitions for hitherto that I've seen before include "Up to this point" , "So far" , "Up till now" , "Up to this time" , "Heretofore (8" .)