Ditch by a castle (4)
I believe the answer is:
moat
(Other definitions for moat that I've seen before include "Water round a castle" , "quantity of water" , "Castle surround" , "Water-filled defensive trench" , "Water around castle" .)
I believe the answer is:
moat
(Other definitions for moat that I've seen before include "Water round a castle" , "quantity of water" , "Castle surround" , "Water-filled defensive trench" , "Water around castle" .)