Get a larger size (4)

I believe the answer is:

grow

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'get' is the definition.
(I know that get can be written as grow)

I don't understand how the rest of the clue works.

(Other definitions for grow that I've seen before include "Expand" , "Swell" , "Develop - propagate" , "Become larger" , "Mature" .)

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

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