Old instrument to strip nevertheless (7)

I believe the answer is:

sackbut

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'old instrument' is the definition.
(I've seen this before)

'strip nevertheless' is the wordplay.
'strip' becomes 'sack' (I am not sure about this - if you are sure you should believe this answer much more).
'nevertheless' becomes 'but' (I've seen this in another clue).
'sack'+'but'='SACKBUT'

'to' is the link.

Can you help me to learn more?

(Other definitions for sackbut that I've seen before include "antique instrument" , "music maker" , "Medieval form of trombone" , "one blows into it" , "music-maker" .)

I've seen this clue in The Globe and Mail.

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