Engineers fail to turn down supplier (5)

I believe the answer is:

eider

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'down supplier' is the definition.
'eider' can be an answer for 'down' (I've seen this in another clue). I'm not sure about the 'supplier' bit.

'engineers fail to turn' is the wordplay.
'engineers' becomes 're' (abbreviation for Royal Engineers).
'fail' becomes 'die' (synonyms).
'to turn' shows that the letters should be reversed in order.
're'+'die'='redie'
'redie' written backwards gives 'EIDER'.

Can you help me to learn more?

(Other definitions for eider that I've seen before include "Species of duck" , "Breed of duck" , "Duck with soft feathers" , "Duck supplying down" , "Down comes from this" .)

I've seen this clue in The Guardian.

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