The phrase "largest clock" is correct and usable in written English
You can use it when you are implying that something is the largest out of its kind. For example, "I found the largest clock in the antique shop."
Largest clock in the world is the Colgate time piece on Jersey waterfront.
Mystic, the largest clock the company produces, is made from spun aluminum, which won't warp or buckle and is light enough to keep shipping costs down.
The Ansonia complex was once one of the largest clock factories in the world before it was converted to residential apartments, some selling for more than a million dollars.
David Sokosh, who restores antique clocks, told me that a beautiful black table clock he displayed ($275) was made around the turn of the century at the old Ansonia factory in Park Slope, once one of the largest clock factories in the world.
Saudi Arabia is hoping that the debut of what is said to be the world's largest clock in Islam's holiest city of Mecca will help establish the city as an alternative time standard to the Greenwich meridian.
Toward the side, two women (Deborah Abramson and Stefanie Smith) twist on chairs beneath a large clock.
She pulled the drawstring open, lifted out a large clock and told me the time.
At the centre is the Zytglogge (2), the tower bearing an implausibly large clock.
A small, functional-looking room with hard leather seats and a wooden table placed squarely under a large clock.
This went on for nearly half an hour, as a large clock on the wall ticked off the minutes.
Atop the symmetrical main facade is a large clock and sculptures of an American eagle and Roman deities.
