You are not finished in time (4)
I believe the answer is:
year
'time' is the definition.
(year is a unit of time)
'you are not finished' is the wordplay.
'you' becomes 'ye' (historical version of 'you').
'not finished' means to remove the last letter.
'are' with its final letter taken away is 'ar'.
'ye'+'ar'='YEAR'
'in' acts as a link.
(Other definitions for year that I've seen before include "Two semesters" , "26 fortnights" , "eg 2004" , "See 33 Across" , "1066, for example" .)