Our etching, though sketchy, improving (10)

I believe the answer is:

retouching

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'improving' is the definition.
The answer and definition can be both related to change as well as being present participle verbs.
Maybe there's an association between them I don't understand?

'our etching though sketchy' is the wordplay.
'our etching' anagrams to 'RETOUCHING'.
Though, I'm unsure how this is indicated.

Can you help me to learn more?

I've seen this clue in The Guardian.

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