Take apart (4)
'take apart' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for undo that I've seen before include "Loosen or reverse" , "Cancel - destroy" , "Bring to nought" , "Loosen; annul" , "Remove the wrapping" .)
'take apart' is the definition.
(synonyms)
This is all the clue.
(Other definitions for dismantle that I've seen before include "Unrig" , "To demolish" , "Take to pieces" , "strike" , "Strip down" .)