Defense mechanism (4)
I believe the answer is:
fort
(Other definitions for fort that I've seen before include "castle, perhaps" , "& 4 Down Army post in USA" , "Keep" , "Citadel" , "William in Scotland" .)
I believe the answer is:
fort
(Other definitions for fort that I've seen before include "castle, perhaps" , "& 4 Down Army post in USA" , "Keep" , "Citadel" , "William in Scotland" .)