China's standard warning? (3,4)

I believe the answer is:

red flag

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

'china's standard' is the wordplay.
'china' becomes 'Red China' (synonyms).
'standard' becomes 'flag' (I've seen this before).
'red'+'flag'='RED FLAG'

(Other definitions for red flag that I've seen before include "A number of revolutionaries" , "Warning to stop" , "Left-wing symbol" , "Sign of trouble" , "Emblem of socialism" .)

I've seen this clue in The Telegraph.

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