Mark with two points (5)
I believe the answer is:
colon
I believe this is a double definition.
'mark' is the first definition.
(I know that colon is a type of punctuation)
'two points' is the second definition.
(I've seen this in another clue)
'with' acts as a link.
(Other definitions for colon that I've seen before include "Part of body; two dots" , ": - bit of the gut" , "unit of foreign currency" , "Panamanian port" , "Part of intestines" .)