Witnesses lone rooks flying (7-2)

I believe the answer is:

lookers-on

'witnesses' is the definition.
(people looking at something)

'lone rooks flying' is the wordplay.
'flying' is an anagram indicator (letters fly around into new positions).
'lone'+'rooks'='lonerooks'
'lonerooks' is an anagram of 'LOOKERS-ON'.

(Another definition for lookers-on that I've seen is " Witnesses".)

I've seen this clue in The Times.

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