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' means one lot of letters goes inside another.
'nil' going around '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?)" .)