Four-thirty, another half-hour clock face used interchangeably with the rest of the set as 'time' iconography rather than a precise marker. It's a textbook example of an emoji that exists purely for completeness — Unicode included the full 24-piece set so no single hour would be missing, even though almost nobody needs that granularity.
Keywords: 30, 4, 4:30, clock, four, four-thirty, thirty, time