Success problem sounds engaging (7)
I believe the answer is:
winsome
'engaging' is the definition.
(I've seen this before)
'success problem sounds' is the wordplay.
'success' becomes 'win' (I've seen this in another clue).
'problem' becomes 'sum' (arithmetic problem).
'sounds' shows a homophone (sound like).
'sum' is a homophone of 'some'.
'win'+'some'='WINSOME'
(Other definitions for winsome that I've seen before include "Attractive, engaging" , "Charming - sweet" , "Attractive - I'm so new (anag)" , "Appealingy attractive" , "Fetching" .)