An important occasion for an Eastern airway (5)

I believe the answer is:

event

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'an important occasion' is the definition.
'event' can be an answer for 'occasion' (I've seen this before). I'm not sure about the 'an important' bit.

'an eastern airway' is the wordplay.
'an eastern' becomes 'e'.
'airway' becomes 'vent' (I can't justify this - if you can you should give a lot more credence to this answer).
'e'+'vent'='EVENT'

'for' acts as a link.

Can you help me to learn more?

(Other definitions for event that I've seen before include "Race contest; occasion" , "Thing that happens" , "Something going on" , "Occurence, happening" , "case" .)

I've seen this clue in The Globe and Mail.

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