Progresses boards (4,2)

I believe the answer is:

gets on

I believe this clue is a double definition.

'progresses' is the first definition.
('get on' can be a synonym of 'progress')

'boards' is the second definition.
(eg to board a train is to get on it)

(Another definition for gets on that I've seen is " Makes progress".)

I've seen this clue in the Sydney Morning Herald.

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