Tendons (6)
I believe the answer is:
sinews
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">tendons</span>' is the definition.<br/ ><span class="explanation-format__explanation">('sinew' can be a synonym of 'tendon')</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for sinews that I've seen before include "They connect muscle to bone" , "Tissue connecting muscles to bones" , "Tough tissues joining muscles to bone" , "Tissues connecting muscles to bones" , "Power" .)