Water nymphs (6)
I believe the answer is:
naiads
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">water nymphs</span>' is the definition.<br/ ><span class="explanation-format__explanation">(nymphs in Greek myth)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for naiads that I've seen before include "Water-nymphs" , "Sprites" , "River nymphs" , "Female swimmers" , "Greek water nymphs" .)