This time is not the first (6)
I believe the answer is:
second
I believe this clue is a double definition.
'this time' is the first definition.
(unit of time)
'not the first' is the second definition.
(not the first but the second)
'is' acts as a link.
(Other definitions for second that I've seen before include "Position of runner-up" , "Silver medal position" , "Mo" , "Support, assist" , "Between first and third" .)