Ditch of defense (4)
I believe the answer is:
moat
(Other definitions for moat that I've seen before include "Ditch round castle" , "Defensive water" , "Water-filled ditch around stronghold" , "defensive construction" , "Water round a castle" .)
I believe the answer is:
moat
(Other definitions for moat that I've seen before include "Ditch round castle" , "Defensive water" , "Water-filled ditch around stronghold" , "defensive construction" , "Water round a castle" .)