Harmful file corrupted in computer (7)
I believe the answer is:
malefic
'harmful' is the definition.
(I've seen this in another clue)
'file corrupted in computer' is the wordplay.
'corrupted' indicates an anagram.
'in' indicates putting letters inside.
'computer' becomes 'Mac' (Apple Mac computer).
'file' with letters rearranged gives 'lefi'.
'lefi' put inside 'mac' is 'MALEFIC'.
(Other definitions for malefic that I've seen before include "Having an evil influence" , "Baleful" , "Causing harm" .)