In time, deserter makes mistakes (6)
I believe the answer is:
errata
'mistakes' is the definition.
(erratum is a kind of mistake)
'in time deserter' is the wordplay.
'in' means one lot of letters goes inside another.
'time' becomes 'era' (I've seen this before).
'deserter' becomes 'rat' (I've seen this before).
'era' enclosing 'rat' is 'ERRATA'.
'makes' is the link.
(Other definitions for errata that I've seen before include "List of printing mistakes" , "Misprints in a book" , "Corrigenda" , "List of text corrections to be made in a publication" , "List of mistakes (in book)" .)