Deed used for legal battle (6)
I believe the answer is:
action
This could be a double definition.
'deed' is the first definition.
(I've seen this before)
'legal battle' is the second definition.
'action' can be an answer for 'battle' (military action). I'm not certain of the 'legal' bit.
'used for' is the link.
Can you help me to learn more?
(Other definitions for action that I've seen before include "Legal proceeding brought by one party against another" , "Accomplishment" , "Court case" , "Deed, maybe battle" , "Film director's cry?" .)