Trimming rear seal (9)

I believe the answer is:

tailoring

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'trimming' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Perhaps there's an association between them I don't understand?

'rear seal' is the wordplay.
'rear' becomes 'tail' (tail is a kind of rear).
'seal' becomes 'oring' (I have seen 'Circular seal ' mean 'o-ring' so perhaps 'seal' could also mean 'o-ring').
'tail'+'oring'='TAILORING'

Can you help me to learn more?

(Another definition for tailoring that I've seen is " Making clothes".)

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