One text contains just over a hundred mistakes (9)

I believe the answer is:

solecisms

'mistakes' is the definition.
(I know this)

'one text contains just over a hundred' is the wordplay.
'one' becomes 'sole' (synonyms).
'text' becomes 'SMS' (abbreviation for Short Message Service).
'contains' is an insertion indicator.
'just over a hundred' becomes 'ci' (s0s in Roman numerals).
'sole'+'sms'='solesms'
'solesms' enclosing 'ci' is 'SOLECISMS'.

(Another definition for solecisms that I've seen is " Grammatical errors".)

I've seen this clue in The Independent.

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