Possibly wane afresh (4)
I believe the answer is:
anew
'afresh' is the definition.
(synonyms)
'possibly wane' is the wordplay.
'possibly' indicates an anagram.
'wane' is an anagram of 'ANEW'.
(Other definitions for anew that I've seen before include "Afresh" , "Once more (poetic)" , "From the beginning again" , "Wane in a different way, again" , "Again but differently" .)