Mistake translating “maturer” (7)
I believe the answer is:
erratum
'mistake' is the definition.
(I know that erratum is a type of mistake)
'translating maturer' is the wordplay.
'translating' indicates anagramming the letters.
'maturer' is an anagram of 'ERRATUM'.
(Other definitions for erratum that I've seen before include "mistake in text" , "Published correction" , "something wrong?" , "gaffe" , "Slip" .)