Ultimately score after extra time (3)
I believe the answer is:
era
'time' is the definition.
(an era is a period of time)
'ultimately score after extra' is the wordplay.
'ultimately' indicates one should take the final letters.
The final letters of 'score after extra' are 'ERA'.
(Other definitions for era that I've seen before include "Epoch, period" , "Are involved in time span" , "Important time" , "day" , "Period of alteration" .)