Precarious structure (5,2,5)
I believe the answer is:
house of cards
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">precarious structure</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 house of cards that I've seen before include "building that might fall over" , "Flimsy structure" , "Unstable scheme" .)