Some pretty poor mistake (4)

I believe the answer is:

typo

'mistake' is the definition.
(typographical error)

'some pretty poor' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'TYPO' is hidden in the letters of 'pretty poor'.

(Other definitions for typo that I've seen before include "Printer's error" , "Misprint" , "Small keyboarding error" , "Spelling mistake" , "Literal error in printed matter, in short" .)

I've seen this clue in The Telegraph.

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