Carelessly lazy (13)
I believe the answer is:
lackadaisical
'carelessly lazy' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for lackadaisical that I've seen before include "Languid and ineffectual" , "Careless and lazy" , "Carelessly lazy" , "Indolent" , "Spiritless" .)