Very, very good flag (5,5)

I believe the answer is:

jolly roger

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'flag' is the definition.
(Jolly Roger is an example)

'very very good' is the wordplay.
'very' becomes 'jolly' (I've seen this before).
'very good' becomes 'roger' (I can't justify this - if you can you should believe this answer much more).
'jolly'+'roger'='JOLLY ROGER'

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(Other definitions for jolly roger that I've seen before include "In the main a fearful sight" , "standard not welcomed in the main" , "Pirate flag" , "standard for boarders?" , "Pirates' flag" .)

I've seen this clue in The Times.

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