Wrongful arrest? An error (15)

I believe the answer is:

misapprehension

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'an error' is the definition.
(thesaurus)

'wrongful arrest?' is the wordplay.
'wrongful' becomes 'mis' (I am not sure about this - if you are sure you should believe this answer much more).
'arrest?' becomes 'apprehension' (synonyms).
'mis'+'apprehension'='MISAPPREHENSION'

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(Other definitions for misapprehension that I've seen before include "Mistaken belief" , "wrong understanding" , "False impression" .)

I've seen this clue in The Daily Express.

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