Pledge; invective (4)
I believe the answer is:
oath
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">pledge</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">invective</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ ></span>
(Other definitions for oath that I've seen before include "gadzooks!" , "Vow, sworn word" , "Curse or solemn word" , "Solemn promise to tell the truth or be loyal" , "in court, we take it" .)