Lazy bachelor one unemployed (4,4)
I believe the answer is:
bone idle
'lazy' is the definition.
(I've seen this before)
'bachelor one unemployed' is the wordplay.
'bachelor' becomes 'B' (abbreviation e.g. BA=Bachelor of Arts).
'unemployed' becomes 'idle' (associated in meaning).
'b'+'one'+'idle'='BONE-IDLE'
(Other definitions for bone idle that I've seen before include "Really lazy in ossified way" , "Very lazy, may be ossified?" , "Extremely inactive" , "Very lazy, from the marrow out" , "Very, lazy, almost ossified" .)