Spiral ear cavity (7)
I believe the answer is:
cochlea
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">spiral ear cavity</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 cochlea that I've seen before include "Coiled tube in the inner ear" , "Snail-shaped tube in the inner ear" , "A cloche (anag) - spiral cavity of the inner ear" , "Spiral tube in inner ear" , "there's a cavity, as we hear" .)