Revert (4)
'revert' is the definition.
(I know that revert can be written as return)
This is all the clue.
(Other definitions for return that I've seen before include "Come back with a formal report on transactions" , "Give or come back" , "Come back; profit" , "Key on computer" , "Come/go back" .)
'revert' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for undo that I've seen before include "Dismantle - destroy" , "Bring to nought" , "Reverse effect of" , "Take apart" , "Cause to become loose" .)