The phrase "a small opening at" is correct and usable in written English.
It can be used to describe a specific location or feature that is characterized by a small gap or hole.
Example: "The cave had a small opening at the base, allowing just enough light to filter through."
Alternatives: "a tiny gap at" or "a narrow aperture at".
This clade is united by the osteological character of a small opening at the base of the skull known as the open posterior myodome (OPM).
Finished compost is removed from a small opening at the base of the chamber.
In modern fridges, condensation runs down the walls and into a small opening at the back.
It has a 14-foot chimney at one end and a small opening at the other, which is sealed after all the pottery to be fired is loaded in.
A simple, highly functional tool, a baster consists of a tube an inch or so in diameter that narrows to a small opening at one end and has a large flexible bulb at the other.
Chester House Wins ARLINGTON HEIGHTS, Ill., Aug. 19 -- (AP) Chester House won the Arlington Million today, squeezing through a small opening at the top of the stretch and moving past the small but congested field.
Depending on surgeon's choice, drainage tube could be extracted via incision or through a small opening made at the posterior border of sternomastoid muscle of supraclavicular fossa.
Some recent papers have dealt with the physics and expected performances of caisson breakwaters embodying a U-OWC: seawater flows in and out of these plants through a relatively small opening at the top of a vertical duct instead of entering through a large opening in a vertical wall, as in some conventional OWCs.
Ashworth decided to bomb Nagasaki using radar, but, according to Bockscar's bombardier, Captain Kermit Beahan, a small opening in the clouds at the end of the three-minute bomb run permitted him to identify target features.
The iron works owner, Mario Gallo, donated the door — which has a small opening with an iron flap at eye level — and arrived with a welder last year to install it.
Nearby, "Plinth, Four Areas" from 1969, is basically a flat square of canvas, about seven feet on a side, with a small opening sliced in its top at each corner.
