Citadel (8)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">citadel</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for fortress that I've seen before include "Protective structure" , "Castle" , "Strong point" , "Perhaps keep" , "it's hard to break into" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">citadel</span>' is the definition.<br/ ><span class="explanation-format__explanation">(a citadel is a fortified city)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for fort that I've seen before include "Strategic position" , "& 22 US Army post" , "& 4 Down Army post in USA" , "Defensive stronghold" , "Citadel" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">citadel</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for bastion that I've seen before include "A projecting fortification to increase angle of fire" , "Obtains in fortified place or stronghold" , "staunch supporter" , "Stronghold, fortification" , "Fortified place near hostile territory" .)