Reveal, make visible (6)
I believe the answer is:
expose
I believe this is a double definition.
'reveal' is the first definition.
(I know that reveal can be written as expose)
'make visible' is the second definition.
(exposing is a kind of making visible)
(Other definitions for expose that I've seen before include "Reveal, uncover" , "Reveal or unmask" , "outing" , "hazard" , "Open to view" .)