Suspect's excuse (5)
I believe the answer is:
alibi
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">suspect's excuse</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for alibi that I've seen before include "Proof of absence" , "Cover story" , "I bail (anag.)" , "Evidence one was not present" , "Defence used by an accused person" .)