Instrument playable upside down (5)

I believe the answer is:

strad

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

I can't explain the rest of the clue.

(Other definitions for strad that I've seen before include "Famous violin" , "Top-quality violin (abbr.)" , "Valuable violin (colloq.)" , "musical instrument" , "Old, very expensive violin (abbr)" .)

I've seen this clue in the Evening Standard.

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