It's closed for fighting (4)
I believe the answer is:
fist
'it's closed for fighting' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for fist that I've seen before include "Hand with the fingers clenched in the palm" , "Hit with a clenched one" , "duke" , "handwriting?" , "One may deck in a ring" .)