Hard but easily broken (7)
I believe the answer is:
brittle
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">hard but easily broken</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for brittle that I've seen before include "Liable to snap" , "Easily cracked or snapped" , "Fragile" , "Hard but easily broken" , "Hard confectionery made with nuts" .)