They travel gratis to arrange half of league fixtures (9)

I believe the answer is:

stowaways

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'half of league fixtures' is the definition.
Although both the answer and definition are plural nouns, I don't see how one could define the other.

'they travel gratis to arrange' is the wordplay.
I cannot quite understand how this works, but
'travel' could be 'way' (way is a kind of travel) and 'way' is found within the answer.
'to' is present in the answer.
This explanation may well be incorrect...

Can you help me to learn more?

(Another definition for stowaways that I've seen is " The hide aboard to get free passage".)

I've seen this clue in The Independent.

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