Secure computer data that has digital application (8)
I believe the answer is:
nailfile
'that has digital application' is the definition.
(a nail file is applied to or used on digits)
'secure computer data' is the wordplay.
'secure' becomes 'nail' (I've seen this before).
'computer data' becomes 'file' (a computer file).
'nail'+'file'='NAILFILE'
(Other definitions for nailfile that I've seen before include "Manicurist's tool" , "Manicure item" .)