A mark in the stomach? (5)
I believe the answer is:
colon
I believe this is a double definition.
'a mark' is the first definition.
(I know that colon is a type of punctuation)
'the stomach?' is the second definition.
(thesaurus)
'in' is the link.
(Other definitions for colon that I've seen before include "cut short dependency?" , "Stop (on the inside!)" , "Part of body; some punctuation" , "Stop - part of intestine" , "Stop (less than full)" .)