An extremely important station (8)

I believe the answer is:

terminus

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'station' is the definition.
(I know that terminus is a type of station)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for terminus that I've seen before include "End of the line for tram or bus" , "End (of rail line)" , "Last stop" , "journey's end" , "End, extremity" .)

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

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