Transport operative who works on holiday (6)

I believe the answer is:

busman

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'holiday' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.

'transport operative who works on' is the wordplay.
'transport' becomes 'bus' (bus is a kind of transport).
'operative who works' becomes 'man' (I can't explain this - if you can you should give a lot more credence to this answer).
'on' says to put letters next to each other.
'bus'+'man'='BUSMAN'

Can you help me to learn more?

I've seen this clue in The Irish Times.

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