Duty I had with waterway as one who ferries people (4-6)

I believe the answer is:

taxi-driver

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'one who ferries people' is the definition.
I know nothing about this answer so I can't judge whether this works.

'duty i had with waterway' is the wordplay.
'duty' becomes 'tax' (I've seen this in another clue).
'i had' becomes 'i'd' (contraction).
'with' is a charade indicator (letters next to each other).
'waterway' becomes 'river' (I've seen this before).
'tax'+'id'+'river'='TAXI-DRIVER'

'as' acts as a link.

Can you help me to learn more?

I've seen this clue in The Times.

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