Punctuation mark perhaps too freely used (10)
I believe the answer is:
apostrophe
'punctuation mark' is the definition.
(apostrophe is a kind of punctuation mark)
'perhaps too freely used' is the wordplay.
'freely used' indicates anagramming the letters (I've seen this in other clues).
'perhaps'+'too'='perhapstoo'
'perhapstoo' anagrammed gives 'APOSTROPHE'.
(Other definitions for apostrophe that I've seen before include "detail of punctuation" , "Sign of omission" , "Often misplaced punctuation mark" , "Passage addressed to character" , "Mark in exam's" .)