Urn, not too big, cost nothing: goodness, a snip (9)

I believe the answer is:

vasectomy

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'a snip' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Perhaps you can see a link between them that I don't see?

'urn not too big cost nothing goodness' is the wordplay.
'urn' becomes 'vase' (I've seen this before).
'not too big cost nothing' becomes 'cto' (I can't explain this - if you can you should give a lot more credence to this answer).
'goodness' becomes 'my' (both are exclamations of surprise).
'vase'+'cto'+'my'='VASECTOMY'

Can you help me to learn more?

(Another definition for vasectomy that I've seen is " Male contraceptive measure".)

I've seen this clue in The Guardian.

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