Bone incorporated hints of unusual surgery (5)
I believe the answer is:
incus
'bone' is the definition.
(thesaurus)
'incorporated hints of unusual surgery' is the wordplay.
'incorporated' becomes 'inc'.
'hints of' suggests taking the first letters.
The initial letters of 'unusual surgery' is 'us'.
'inc'+'us'='INCUS'
(Other definitions for incus that I've seen before include "Bone in the middle ear" , "anvil (so we hear)" , "Anvil-shaped bone in ear" , "Ear anvil bone" , "part of sound system" .)