Type of mollusc (6)
I believe the answer is:
limpet
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">type of mollusc</span>' is the definition.<br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for limpet that I've seen before include "A shellfish that sticks to rocks or ships" , "Cinging mollusc" , "Shellfish; type of mine" , "Rock lover" , "Sea creature (or person) not easily shifted" .)