Sid's organ playing 'Stop' and 'Roundabout'? (4,5)

I believe the answer is:

road signs

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'stop and roundabout'?' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.

'sid's organ playing' is the wordplay.
'playing' indicates anagramming the letters.
'sids'+'organ'='sidsorgan'
'sidsorgan' with letters rearranged gives 'ROAD SIGNS'.

Can you help me to learn more?

(Other definitions for road signs that I've seen before include "pointers" , "Indications for car driver to observe" .)

I've seen this clue in The Guardian.

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