Joining up the southeastern flank (6)

I believe the answer is:

sewing

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'joining up the' is the definition.
I can't judge whether this definition defines the answer.

'southeastern flank' is the wordplay.
'southeastern' becomes 'se'.
'flank' becomes 'wing' (I've seen this before).
'se'+'wing'='SEWING'

Can you help me to learn more?

(Other definitions for sewing that I've seen before include "Joining by stitching" , "Working with a needle" , "Using a needle and thread" , "Darning" , "Genteel pursuit" .)

I've seen this clue in the Evening Standard.

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