"Mere tools," one says menacingly (5)

I believe the answer is:

rasps

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'mere tools' is the definition.
'rasps' can be an answer for 'tools' (rasp is a kind of tool). I am not sure about the 'mere' bit.

I can't explain the rest of the clue.

Can you help me to learn more?

(Other definitions for rasps that I've seen before include "Scrapes" , "fruit briefly" , "Jars" , "Coarse files" , "speaks hoarsely" .)

I've seen this clue in the Evening Standard.

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