Superfluity (8)
I believe the answer is:
plethora
'superfluity' is the definition.
(I know that superfluity can be written as plethora)
This is all the clue.
(Other definitions for plethora that I've seen before include "Large number" , "flood" , "'Excess, superfluity (8)'" , "More than enough" , "Embarrassment" .)