Instrument taken from bag by Aunt Sally, briefly (7)
I believe the answer is:
sackbut
'instrument' is the definition.
(early type of trombone)
'bag by aunt sally briefly' is the wordplay.
'bag' becomes 'sack' (sack is a kind of bag).
'by' says to put letters next to each other.
'aunt sally' becomes 'butt' (both can mean the subject of criticism).
'briefly' means to remove the last letter.
'butt' with its final letter taken off is 'but'.
'sack'+'but'='SACKBUT'
'taken from' is the link.
(Other definitions for sackbut that I've seen before include "one blows into it" , "one on the slide" , "Ancient musical instrument" , "Old trombone" , "This was in the wind" .)