Action working both ways (4)

I believe the answer is:

deed

I'm a little stuck... Click here to teach me more about this clue!

'both ways' is the definition.

I don't understand how the rest of the clue works.

(Other definitions for deed that I've seen before include "Document showing ownership" , "Legal document for transfer of property" , "Action - legal document" , "Act - exploit - legal document" , "Feat" .)

I've seen this clue in The Mirror.

Want a hint initially instead of a full solution? Install my app