Slips out of shop in time (6)
I believe the answer is:
errata
'slips' is the definition.
(slip can mean an error or mistake)
'shop in time' is the wordplay.
'shop' becomes 'rat' (both can mean to betray someone).
'in' is an insertion indicator.
'time' becomes 'era' (an era is a period of time).
'rat' going inside 'era' is 'ERRATA'.
'out of' acts as a link.
(Other definitions for errata that I've seen before include "(Printing) errors" , "Misprints in a book" , "List of text corrections to be made in a publication" , "List of printing mistakes" , "Mistakes in printed matter" .)