Too much (6)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">too much</span>' is the definition.<br/ ><span class="explanation-format__explanation">(excess of something means too much of it)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for excess that I've seen before include "Glut; surplus" , "Immoderation as in eating, too much" , "Nothing in it, for the Greeks" , "Surfeit; overindulgence" , "debauchery" .)
(Other definitions for excessively that I've seen before include "Overly" , "Overmuch" .)