Hither and thither (2,3,3)
I believe the answer is:
to and fro
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">hither and thither</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 to and fro that I've seen before include "From place to place" , "both ways" , "Shuttle's motion" , "Backwards and forwards" , "Directions of oscillation" .)