Hold on to (6)
I believe the answer is:
retain
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">hold on to</span>' is the definition.<br/ ><span class="explanation-format__explanation">(retaining is a kind of holding on to)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for retain that I've seen before include "Keep; remember" , "Keep in place" , "Hold in position" , "Keep, hold on to something" , "Hire - keep" .)