Catch or catch on (3)

I believe the answer is:

get

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'catch on' is the definition.
(I've seen this in another clue)

I cannot understand how the remainder of the clue works.

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(Other definitions for get that I've seen before include "See 18" , "Procure from vegetables" , "Receive; obtain" , "Acquire" , "Fetch or obtain" .)

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

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