Woodwind instrument made from old tree trunk, not large (4)
I believe the answer is:
oboe
'woodwind instrument' is the definition.
(oboe is a kind of woodwind instrument)
'old tree trunk not large' is the wordplay.
'old' becomes 'o' (abbreviation).
'tree trunk' becomes 'bole' (term for the trunk of a tree).
'not' is a deletion indicator.
'large' becomes 'L' (eg in clothes sizes).
'bole' with 'l' taken away is 'boe'.
'o'+'boe'='OBOE'
'made from' acts as a link.
(Other definitions for oboe that I've seen before include "Walk with exaggerated movements" , "it's blown" , "Orchestral piece" , "Source of music" , "Cor anglais in its family" .)