Location of vision, it’s said? (4)
I believe the answer is:
site
'location' is the definition.
(site is a kind of location)
'vision it's said?' is the wordplay.
'vision' becomes 'sight' ('sight' can be a synonym of 'vision').
'it's said?' indicates a 'sounds like' (homophone) clue.
'sight' sounds like 'SITE'.
'of' acts as a link.
(Other definitions for site that I've seen before include "Location; locate" , "Locality" , "Situation (of a building)" , "Spot, location" , "Where something is located" .)