Protective hat (6)
I believe the answer is:
helmet
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">protective hat</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for helmet that I've seen before include "personal protection" , "Biker's headgear" , "Armor for the head" , "Top Gear" , "Hard hat" .)