Immoderate amount (6)
(Other definitions for excess that I've seen before include "Plethora" , "Too much - going too far" , "Nothing in it, for the Greeks" , "More than usual" , "Intemperance" .)
(Other definitions for surfeit that I've seen before include "Fustier (anag)" , "excessive amount" , "it's more than one needs" , "stuff, once" , "Excess, glut" .)