Switch positions, crossing oceans in slack period for travel (9)

I believe the answer is:

offseason

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'slack period for travel' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.

'switch positions crossing oceans' is the wordplay.
'switch positions' becomes 'off on' (off and on are positions on a switch).
'crossing' is an insertion indicator (to cross can mean to go over or around).
'oceans' becomes 'seas' ('sea' can be a synonym of 'ocean').
'offon' placed around 'seas' is 'OFFSEASON'.

'in' acts as a link.

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I've seen this clue in The Telegraph.

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