A century, maybe, but it's not over (3)
I believe the answer is:
ton
'a century' is the definition.
(both can mean one hundred of something)
'but it's not over' is the wordplay.
'not' anagrams to 'TON'.
But, I am not sure how the anagram is indicated.
'maybe' is the link.
Can you help me to learn more?
(Other definitions for ton that I've seen before include "A slang 100mph - heavy" , "2240lbs" , "Speed" , "20 cwt" , "A slang 100 mph" .)