Bone fragment turning up on outskirts of Ithaca (5)
I believe the answer is:
tibia
'bone' is the definition.
(tibia is a kind of bone)
'fragment turning up on outskirts of ithaca' is the wordplay.
'fragment' becomes 'bit' (bit is a kind of fragment).
'turning up' says the letters should be written in reverse.
'on' is a charade indicator (letters next to each other).
'outskirts of' says to hollow out the word (remove centre letters).
'ithaca' with its centre taken out is 'ia'.
'bit' written backwards gives 'tib'.
'tib'+'ia'='TIBIA'
(Other definitions for tibia that I've seen before include "part of skeleton" , "Bone of the lower leg" , "The large shinbone" , "Bone in osso bucco" , "The formal shinbone" .)