Finished being tense (4)
I believe the answer is:
past
This clue is a double definition.
'finished' is the first definition.
(I've seen this in another clue)
'being tense' is the second definition.
(I've seen this before)
(Other definitions for past that I've seen before include "Gone by in time" , "historical times" , "Second visitor in 5 [A CHRISTMAS CAROL]" , "Bygone" , "Finished, gone" .)