Opening vacation (6)
I believe the answer is:
recess
This clue might be a double definition.
'opening' is the first definition.
The definition and answer can be both acts as well as being singular nouns.
Maybe you can see an association between them that I can't see?
'vacation' is the second definition.
(I know that recess is a type of vacation)
Can you help me to learn more?
(Other definitions for recess that I've seen before include "Space set back in wall" , "Temporary suspension of business" , "'Niche, inlet (6)'" , "Niche, alcove" , "Small set-back space" .)