This is a text timestamp recording when an operator last issued a manual clear against the bytes and frames of broadcast, Layer-2 multicast, or unknown-unicast traffic that exceeded this port's flood/storm-control threshold and were dropped tracked in the general life-to-date running counter for this metric, which an operator can zero with a manual clear -- which is why a clear-time field is defined alongside it. On this element it is what separates a flood-containment drop count of zero that means genuinely no matching activity from one that means someone recently reset the counters, and for a Stats bin specifically it tells you whether the totals you're comparing against other Stats bins were reset partway through, making them not directly comparable. For instance, a clear time that falls in the middle of what should have been a full life-to-date window explains why this particular Stats bin's flood-containment drop totals are lower than the otherwise-similar bins around it in the series.