Chess castle (4)
I believe the answer is:
rook
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">chess castle</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for rook that I've seen before include "Gregarious black bird" , "Ringing in the ears" , "Man in game" , "Fleece - bird" , "Swindle (colloq.); bird" .)