Get wrong mark, raised erroneously (7)
I believe the answer is:
misread
'get wrong' is the definition.
(thesaurus)
'mark raised erroneously' is the wordplay.
'mark' becomes 'm' ().
'erroneously' indicates anagramming the letters.
'raised' anagrammed gives 'isread'.
'm'+'isread'='MISREAD'
(Other definitions for misread that I've seen before include "Take the wrong way" , "wrongly interpreted" .)