Vent, aperture (7)
I believe the answer is:
orifice
I believe this is a double definition.
'vent' is the first definition.
(I've seen this before)
'aperture' is the second definition.
(I've seen this in another clue)
(Other definitions for orifice that I've seen before include "Finding opening" , "Hole in the head, perhaps?" , "Bodily opening, mouth of cavity" , "provided by gold and diamonds" , "8 [OPENING]" .)