Ring out again, perhaps, to complete annulment (6)
I believe the answer is:
repeal
'annulment' is the definition.
(synonyms)
'ring out again perhaps to complete' is the wordplay.
I cannot quite see how this works, but
'ring' could be 'peal' (pealing is a kind of ringing) and 'peal' is located in the answer.
'again' could be 're' and 're' is located in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for repeal that I've seen before include "reverse" , "Annul a law" , "reversal of act" , "Revoke, a law say" , "Annulment" .)