Stolen files ultimately erased (6)
I believe the answer is:
swiped
'stolen' is the definition.
(swiping is a kind of stealing)
'files ultimately erased' is the wordplay.
'ultimately' indicates one should take the final letters.
'erased' becomes 'wiped' (to erase is to delete or wipe).
The last letter of 'files' is 's'.
's'+'wiped'='SWIPED'
(Other definitions for swiped that I've seen before include "Struck; stolen" , "Hit with swinging blow, or slangily stole" , "Nicked (sl.)" , "credit card may be processed thus" .)