Water tester (3)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">water tester</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for toe that I've seen before include "one digit?" , "End of sock" , "Pedal digit" , "Front of shoe" , "Part of foot" .)