Gatwick Express reaching harbour? (7)

I believe the answer is:

airport

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'gatwick' is the definition.
I can't judge whether this defines the answer.

'express reaching harbour?' is the wordplay.
'express' becomes 'air' (I've seen this in another clue).
'reaching' says to put letters next to each other.
'harbour?' becomes 'port' (harbour is a kind of port).
'air'+'port'='AIRPORT'

Can you help me to learn more?

(Other definitions for airport that I've seen before include "Charles de Gaulle, for instance" , "place with lounges for travellers?" , "Heathrow, for example" , "Destination for planes" , "Par trio (anag) -- Charles de Gaulle, say" .)

I've seen this clue in The Sun.

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