Calais cap (5)
I believe the answer is:
beret
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">calais cap</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 beret that I've seen before include "French-style cap" , "Round, brimless cap" , "Felt hat" , "French-style hat" , "Flattish felt cap" .)