The point is, it's a blemish (4)
I believe the answer is:
mark
I believe this is a double definition.
'the point' is the first definition.
(thesaurus)
'it's a blemish' is the second definition.
(mark is a kind of blemish)
'is' is the link.
(Other definitions for mark that I've seen before include "Scratch - German coin" , "Visible impression" , "Man's name; target" , "Trace" , "The second Gospel" .)