Back up, on a PC (4)
I believe the answer is:
undo
(Other definitions for undo that I've seen before include "Untie, loosen" , "Loosen; annul" , "Open buttons or ruin" , "set free" , "Ruin prospects of; cancel" .)
I believe the answer is:
undo
(Other definitions for undo that I've seen before include "Untie, loosen" , "Loosen; annul" , "Open buttons or ruin" , "set free" , "Ruin prospects of; cancel" .)