Giant redwood (7)
I believe the answer is:
sequoia
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">giant redwood</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 sequoia that I've seen before include "California redwood tree" , "Giant California redwood" , "Enormous evergreen" , "big tree" , "Giant conifer" .)