Applied gypsum in your cups (9)

I believe the answer is:

plastered

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'applied gypsum' is the definition.
The definition and answer can be both to do with contact as well as being past participle verbs.
Maybe you can see a link between them that I don't see?

I can't explain the remainder of the clue.

Can you help me to learn more?

(Other definitions for plastered that I've seen before include "under the table?" , "wasted" , "spread" , "Very drunk (colloq.)" , "Rendered" .)

I've seen this clue in the Sydney Morning Herald.

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