Mark of disgrace or infamy (6)
I believe the answer is:
stigma
I believe this clue is a double definition.
'mark of disgrace' is the first definition.
(I've seen this in another clue)
'infamy' is the second definition.
(thesaurus)
(Other definitions for stigma that I've seen before include "Sign of disgrace" , "Disgraceful sign" , "Mark of shame or social disgrace" , "Bad mark" , "Brand or mark of infamy" .)