Punctuation mark: misused too, perhaps (10)
I believe the answer is:
apostrophe
'punctuation mark' is the definition.
(apostrophe is a kind of punctuation mark)
'misused too perhaps' is the wordplay.
'misused' is an anagram indicator.
'too'+'perhaps'='tooperhaps'
'tooperhaps' is an anagram of 'APOSTROPHE'.
(Other definitions for apostrophe that I've seen before include "address?" , "rhetorical digression" , "Passage addressed to character" , "Letter omission indicator" , "At which point discarded letters" .)