The cheapest part is better avoided (4)

I believe the answer is:

pest

I'm a little stuck... Click here to teach me more about this clue!

'part is better avoided' is the definition.
I can't judge whether this definition defines the answer.

'the cheapest' is the wordplay.
'PEST' is hidden in amongst the letters.
However, I'm unsure how this is indicated.

Can you help me to learn more?

(Other definitions for pest that I've seen before include "Annoying person" , "Destructive creature" , "Annoying nuisance" , "Plague" , "Troublesome man or animal" .)

I've seen this clue in the Evening Standard.

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