An unreal performance by Strummer? (3,6)

I believe the answer is:

air guitar

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If this is the answer I cannot explain how the clue works.

(Other definitions for air guitar that I've seen before include "Imaginary instrument played by rock fans!" , "Instrumental object that's non-existent" , "Imaginary stringed instrument" , "Imaginary instrument that one pretends to play" , "Just imagine playing this" .)

I've seen this clue in The Times.

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