Strength, potency (5)
I believe the answer is:
power
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">strength</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I know that power is a type of strength)</span><br/ ><br/ >'<span class="explanation-format__original">potency</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ ></span>
(Other definitions for power that I've seen before include "Force - potentiality" , "Ability (to do something)" , "Supremacy, force" , "Strength, force" , "Strength or authority" .)