Nothing about a form of digital protection (4)
I believe the answer is:
nail
'form of digital protection' is the definition.
'nothing about a' is the wordplay.
'nothing' becomes 'nil' (eg nil is zero in football).
'about' indicates putting letters inside.
'nil' enclosing 'a' is 'NAIL'.
(Other definitions for nail that I've seen before include "Perfectly execute" , "one under the hammer" , "Finger end; fasten" , "Fix with a metal spike" , "Fixer (on finger?)" .)