Very lazy (4,4)
I believe the answer is:
bone idle
'very lazy' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for bone idle that I've seen before include "staff may be?" , "Really lazy in ossified way" , "Utterly lazy, won't do a tap" , "Very lazy from the inside out" , "Extremely inactive" .)