Different mum missing the beginning (5)

I believe the answer is:

other

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'different' is the definition.
(similar in meaning)

I don't understand the remainder of the clue.

(Other definitions for other that I've seen before include "Alternate; additional" , "One may be significant" , "Different; additional" , "Different, not the same one or this one" , "Remaining" .)

I've seen this clue in The Daily Express.

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