Possible Clues:

• Geometry postulate
• Man supporting a vote that's assumed to be valid
• You may take it that it's 10.10 in the morning
• Generally accepted truism
• "Good things come to those who wait," e.g.
• It's assumed
• Saw a hobnob rejected over chocolate centre
• "Lost time is never found again," for one
• Plainly true proposition
• Generally accepted proposition