Defence of being elsewhere (5)
I believe the answer is:
alibi
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">defence of being elsewhere</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for alibi that I've seen before include "Legal proof of innocence" , "Courtroom evidence" , "Evidence one was elsewhere at time of crime" , "I bail (anag.)" , "Justification" .)