Home ground unfinished, left to train abroad? (9)

I believe the answer is:

interrail

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'abroad?' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.

'home ground unfinished left to train' is the wordplay.
'home ground unfinished left' becomes 'inter' (I can't explain this - if you can you should give a lot more credence to this answer).
'to train' becomes 'rail' (I've seen this before).
'inter'+'rail'='INTERRAIL'

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