Irrevocable (5)
I believe the answer is:
final
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">irrevocable</span>' is the definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for final that I've seen before include "Not to be altered" , "Last match in a competition" , "Coming at the end" , "Like one's journey to cemetery" , "Concluding" .)