Examples:

• Frankly, Mrs. Grant is a woman of a certain age.
• Frankly, Mrs. Grant is a woman of a certain age.
• It's a social network for eligible women of a certain age.
• The clothes are of a person of a certain age.
• You and I are women of a certain age.
• I've become a woman of a certain age.
• I won't be of a certain age for another ten years.
• I won't be of a certain age for another ten years.
• You know, a single man of a certain age who lives alone.
• And he must be French and of a certain age.