Impressed by the writer, can much upset one? (9)

I believe the answer is:

mumchance

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'one?' is the definition.
Both the answer and definition are adjectives.
Maybe there's a link between them I don't understand?

'impressed by the writer can much upset' is the wordplay.
'impressed by' indicates putting letters inside.
'the writer' becomes 'me' (the person who wrote the clues).
'upset' indicates an anagram.
'can'+'much'='canmuch'
'canmuch' anagrammed gives 'umchanc'.
'me' placed around 'umchanc' is 'MUMCHANCE'.

Can you help me to learn more?

(Other definitions for mumchance that I've seen before include "dumb" , "soft" .)

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