Foremost pair, one linked to Joseph's partner (7)

I believe the answer is:

primary

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'foremost' is the definition.
(thesaurus)

'pair one linked to joseph's partner' is the wordplay.
'pair' becomes 'pr' (abbreviation).
'one' becomes 'i' (Roman numeral).
'linked to' means one lot of letters go next to another.
'joseph's partner' becomes 'mary' (I can't explain this - if you can you should believe this answer much more).
'pr'+'i'+'mary'='PRIMARY'

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(Other definitions for primary that I've seen before include "Of the first order" , "Cardinal" , "Principal" , "Paramount" , "The colours from which all others can be made" .)

I've seen this clue in The Guardian.

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