Apply (force) (5)
I believe the answer is:
exert
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">apply force</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for exert that I've seen before include "Cause (oneself) to make a strenuous effort" , "Apply (pressure)" , "Make a great effort" , "Bring quality or influence into play" , "Put to use, vigorously" .)