Tusked whale (7)
I believe the answer is:
narwhal
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">tusked whale</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 narwhal that I've seen before include "Ocean mammal" , "Small tusked whale" , "Animal with large spiral tusk" , "Breed of small whale" , "aquatic mammal" .)