Giant grass (6)
I believe the answer is:
bamboo
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">giant grass</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 bamboo that I've seen before include "Spotted tile; carnival mask" , "Thick tropical cane" , "Type of cane" , "Fast-growing woody grass" , "stick" .)