Seeing sense (5)
I believe the answer is:
sight
I believe this is a double definition.
'seeing' is the first definition.
(I know that seeing can be written as sight)
'sense' is the second definition.
(sight or vision is a sense)
(Other definitions for sight that I've seen before include "A lot" , "something ugly" , "Device used in aiming" , "good deal" , "Vision, ability to see" .)