Garrisons (5)
I believe the answer is:
forts
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">garrisons</span>' is the definition.<br/ ><span class="explanation-format__explanation">('fort' can be a synonym of 'garrison')</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for forts that I've seen before include "Defensive structures where troops are stationed" , "Castles" , "Strongholds" .)