Wind instrument made from old bone, not new (4)
I believe the answer is:
oboe
'wind instrument' is the definition.
(oboe is a kind of wind instrument)
'old bone not new' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'not' indicates named letters should be taken away.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'bone' with 'n' removed is 'boe'.
'o'+'boe'='OBOE'
'made from' is the link.
(Other definitions for oboe that I've seen before include "Orchestral piece" , "Source of music" , "source of notes" , "Player" , "it's blown" .)