Possible Clues:

• A day has 24 (Abbr.)
• Brief time pieces?
• Parts of yrs
• Nolte-Murphy film "48 ___"
• 6:00, 7:00, 8:00, etc. (Abbr.)
• Timesheet units (abbr.)
• They fill up the day, briefly
• Retail posting: Abbr.
• Stadium thrillers: Abbr.
• Noon and midnight: Abbr.