Successes penning new clues (5)
I believe the answer is:
hints
'clues' is the definition.
('hint' can be a synonym of 'clue')
'successes penning new' is the wordplay.
'successes' becomes 'hits' (hit is a kind of success).
'penning' indicates putting letters inside.
'new' becomes 'n'.
'hits' going around 'n' is 'HINTS'.
(Other definitions for hints that I've seen before include "Slight indications" , "Suggestions" , "Tips" .)