Success spread to her, until now (8)
I believe the answer is:
hitherto
'until now' is the definition.
(hitherto means until the present time)
'success spread to her' is the wordplay.
'success' becomes 'hit' (a hit is a commercial success).
'spread' indicates anagramming the letters.
'to'+'her'='toher'
'toher' is an anagram of 'herto'.
'hit'+'herto'='HITHERTO'
(Other definitions for hitherto that I've seen before include "Previously" , "Up to this point" , "Up till now" , "So far" , "Up to this time" .)