Jack sending poor daughter away (6)

I believe the answer is:

ensign

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'jack' is the definition.
(thesaurus)

I cannot understand how the remainder of the clue works.

(Other definitions for ensign that I've seen before include "Low-ranking naval officer" , "Lowly ranked officer" , "Ship's flag to show nationality" , "Badge, flag" , "Soldier who carries the Colours" .)

I've seen this clue in The Hindu.

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