Failed (9)
(Other definitions for collapsed that I've seen before include "Gave way, caved in" , "Cracked up - gave way" , "Fell apart" , "laid low" .)
(Another definition for gone to pot that I've seen is " Totally deteriorated".)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">failed</span>' is the definition.<br/ ><span class="explanation-format__explanation">(similar in meaning)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for unsuccessful that I've seen before include "Not accomplishing aim" , "bringing no reward" , "Not achieving one's aim" .)