All eastern fork roads are narrow passages (9)

I believe the answer is:

alleyways

I'm a little stuck... Click here to teach me more about this clue!

'narrow passages' is the definition.
(I know this)

'all eastern fork roads are' is the wordplay.
'eastern' says the letters should be written backwards (letters written right to left or east to west).
'fork' becomes 'wye' (I've seen this in another clue).
'roads are' becomes 'ays' (I can't explain this - if you can you should give a lot more credence to this answer).
'wye' back-to-front is 'eyw'.
'all'+'eyw'+'ays'='ALLEYWAYS'

Can you help me to learn more?

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

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