Japanese fencing partly broken down (5)
I believe the answer is:
kendo
'japanese fencing' is the definition.
(I've seen this in another clue)
'partly broken down' is the wordplay.
'partly' says the answer is hidden in the clue (part of the clue is used).
'KENDO' is hidden in the letters of 'broken down'.
(Other definitions for kendo that I've seen before include "Asian fighting" , "Japanese fighting" , "wooden fencing?" , "Marrtial art" , "Combat" .)