Issue and break NYC orders on subway safety (9,5)

I believe the answer is:

emergency brake

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'subway safety' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe there's an association between them I don't understand?

'issue and break nyc orders' is the wordplay.
'issue' becomes 'emerge' (synonyms).
'and' means one lot of letters go next to another.
'orders' indicates an anagram.
'break'+'nyc'='breaknyc'
'breaknyc' with letters rearranged gives 'ncybrake'.
'emerge'+'ncybrake'='EMERGENCY BRAKE'

'on' is the link.

Can you help me to learn more?

I've seen this clue in the Sydney Morning Herald.

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