Bone idle new carer under supervision initially (5)
I believe the answer is:
incus
'bone' is the definition.
(thesaurus)
'idle new carer under supervision initially' is the wordplay.
'initially' says to take the initial letters.
The initial letters of 'idle new carer under supervision' is 'INCUS'.
(Other definitions for incus that I've seen before include "anvil (so we hear)" , "Anvil-shaped bone in ear" , "Middle-ear bone" , "Ear anvil bone" , "part of sound system" .)