Round Three over, finally getting the bell (6)
I believe the answer is:
ringer
'the bell' is the definition.
(I've seen this in other clues)
'round three over finally' is the wordplay.
'round' becomes 'ring' (synonyms).
'three over' becomes 'er' (I can't explain this - if you can you should believe this answer much more).
'finally' says to put letters next to each other (some letters go at the end of others).
'ring'+'er'='RINGER'
'getting' is the link.
(Other definitions for ringer that I've seen before include "Campanologist's" , "Campanologist - spitting image" , "someone who shouldn't be competing?" , "See 22" , "American impostor" .)