Short baby struck symptoms heartily? (6)

I believe the answer is:

abrupt

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

I cannot understand how the rest of the clue works.

(Other definitions for abrupt that I've seen before include "brisk" , "Unexpected - terse" , "Sudden; precipitous" , "Sudden, maybe discourteous" , "Unexpected -- precipitous" .)

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

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