Surplus, glut (6)
I believe the answer is:
excess
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">surplus</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >'<span class="explanation-format__original">glut</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ ></span>
(Other definitions for excess that I've seen before include "Too much - going too far" , "debauchery" , "Over and above what's needed" , "Outrageous behaviour; extra payment" , "Plethora" .)