Single-click is not possible, hopefully you can muster the energie
to click one more time :) .
Here you go:
Private Sub Worksheet_BeforeDoubleClick(ByVal Target As Range, Cancel As Boolean)
If Intersect(Target, Range("B2:G" & Rows.Count)) Is Nothing Then Exit Sub
If Target.Value = vbNullString And Target.Offset(0, -1).Value <> vbNullString Then
Target.Value = Time
Remember to unblock the cells you don't want to protect.
Format cells to display time the way you want.
Monday, Tuesday and Thursday are usually the days I'll respond. Bear this in mind when awaiting a reply.