Over tense (4)
I believe the answer is:
past
I believe this clue is a double definition.
'over' is the first definition.
(both can mean finished)
'tense' is the second definition.
(I know that past is a type of tense)
(Other definitions for past that I've seen before include "Days gone by" , "tense" , "A person's earlier life history" , "Beyond" , "Second visitor in 5 [A CHRISTMAS CAROL]" .)