Sailor reaches duchy's borders late (5)

I believe the answer is:

tardy

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'late' is the definition.
(I know that late can be written as tardy)

'sailor reaches duchy's borders' is the wordplay.
'sailor reaches' becomes 'tar' (I can't justify this - if you can you should give a lot more credence to this answer).
'borders' means to remove the middle letters (only the edge or border letters remain).
'duchy' with its middle removed is 'dy'.
'tar'+'dy'='TARDY'

Can you help me to learn more?

(Other definitions for tardy that I've seen before include "Behindhand" , "Rather late" , "Backward" , "Dilatory" , "Belated" .)

I've seen this clue in The Daily Express.

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