What the passenger pays to get on? (4)

I believe the answer is:

fare

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'get on?' is the definition.
(I've seen this in another clue)

I don't understand how the rest of the clue works.

(Other definitions for fare that I've seen before include "Get on - passenger - provisions" , "What traveller pays" , "Range of food; travel" , "Cost of travel" , "Food for the cost of a journey" .)

I've seen this clue in the Evening Standard.

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