Mess that makes sense? (5)
I believe the answer is:
sight
This clue is a double definition.
'mess' is the first definition.
(I know that mess can be written as sight)
'sense?' is the second definition.
(sight or vision is a sense)
'that makes' is the link.
(Other definitions for sight that I've seen before include "Glimpse" , "View" , "Sense" , "Show" , "A lot" .)