In time, traitor will make mistakes (6)
I believe the answer is:
errata
'mistakes' is the definition.
(an erratum is a mistake in a printed work)
'in time traitor' is the wordplay.
'in' is an insertion indicator.
'time' becomes 'era' (an era is a period of time).
'traitor' becomes 'rat' (rat can mean a treacherous person).
'era' placed around 'rat' is 'ERRATA'.
'will make' is the link.
(Other definitions for errata that I've seen before include "Mistakes in printing or writing" , "Boobs in a book" , "Corrigenda" , "List of printed mistakes" , "corrected mistakes" .)