A rope must be twisted by a vermin catcher (9)

I believe the answer is:

mousetrap

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'a vermin catcher' is the definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.

'a rope must be twisted' is the wordplay.
'be twisted' indicates anagramming the letters.
'a'+'rope'+'must'='aropemust'
'aropemust' anagrammed gives 'MOUSETRAP'.

'by' acts as a link.

Can you help me to learn more?

(Other definitions for mousetrap that I've seen before include "Snare for vermin" , "Rodent catcher" , "For instance, old Cheshire" , "pest control device" , "This may take the Mickey" .)

I've seen this clue in The Irish Independent.

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