Possible Clues:

• Wee hour
• Wee hr
• When some bars close
• Wee hr. of the morning
• Clock change hr. (though most do it sooner)
• Time for semiannual clock changes: Abbr
• Clock-changing time, for daylight saving time
• When daylight saving begins: Abbr.
• Bar closing time, often
• Fall-back time?