Open to view? About time (5)
I believe the answer is:
'open to view?' is the definition.
(I've seen this before)
'about time' is the wordplay.
'about' becomes 'over' (both can mean around).
'time' becomes 't' (abbreviation).
(Other definitions for overt that I've seen before include "Done in an obvious way" , "Obvious, patent" , "Openly displayed" , "Voter (anag.)" , "Open to view" .)