Instability (4)
I believe the answer is:
flux
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">instability</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 flux that I've seen before include "Excessive discharge of liquid" , "Flow of matter" , "State of constant change" , "Continuous state of change" , "Process of flowing" .)