Replaced the disc after reformatting to protect passwords, essentially (8)
I believe the answer is:
switched
'replaced' is the definition.
'the disc after reformatting to protect passwords essentially' is the wordplay.
'after reformatting' indicates an anagram.
'to protect' is an insertion indicator.
'essentially' says to take the centre.
The middle letter of 'passwords' is 'w'.
'the'+'disc'='thedisc'
'thedisc' is an anagram of 'sitched'.
'sitched' enclosing 'w' is 'SWITCHED'.
(Other definitions for switched that I've seen before include "Exchanged" , "Swapped over" , "could well be beaten" , "Changed course" , "Turned electric appliance on or off" .)