Aperture or opportunity (7)
I believe the answer is:
opening
This clue is a double definition.
'aperture' is the first definition.
(I've seen this in another clue)
'opportunity' is the second definition.
(I know that opening is a type of opportunity)
(Other definitions for opening that I've seen before include "Rent" , "premiere" , "Opportunity; gap" , "break" , "Initial" .)