Odd occurrence (7)
I believe the answer is:
anomaly
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">odd occurrence</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for anomaly that I've seen before include "Special case" , "Aberration" , "Irregularity or inconsistency, deviation from norm" , "A deviation from normal" , "Deviation from the norm or expected" .)