Small picturesque cave (6)
I believe the answer is:
grotto
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">small picturesque cave</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 grotto that I've seen before include "It's left on Dec 24 by Santa and his reindeer" , "Fancy cave" , "Cavern" , "Small cave as at Lourdes" , "(Imitation) cave" .)