Cause residue in cafetiere (7)

I believe the answer is:

grounds

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'cafetiere' is the definition.
I can't tell whether this definition defines the answer.

'cause residue' is the wordplay.
'cause' becomes 'ground'.
'residue' becomes 's' (I can't explain this - if you can you should believe this answer much more).
'ground'+'s'='GROUNDS'

'in' acts as a link.

Can you help me to learn more?

(Other definitions for grounds that I've seen before include "Refuses authority to fly" , "reason" , "enclosure around house" , "Area of enclosed land around a building" , "Reasons" .)

I've seen this clue in The Daily Express.

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