What we do carelessly in writing about an Amercan state? (8)

I believe the answer is:

missouri

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'state?' is the definition.
(Missouri is an example)

I cannot understand how the remainder of the clue works.

(Other definitions for missouri that I've seen before include "Longest river in the US, joining the Mississippi at St Louis" , "State of central US" , "So is rum I alter to the state" , "River joining the Mississippi south of St Louis" , "State south of Iowa" .)

I've seen this clue in The Guardian.

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