Earth movement (8)
I believe the answer is:
landslip
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">earth movement</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 landslip that I've seen before include "Avalanche" , "Fall of earth, stones, etc down slope" , "Rockfall" , "Earth movement" .)