Of a certain age
Definition 1 of 1
Pro Tip 1/3Indirect Age Reference
The phrase implies someone's age without stating it directly, often hinting they are middle-aged or older. 
My neighbor is a gentleman of a certain age who still runs marathons.
Pro Tip 2/3Euphemistic Usage
It's a polite way to mention someone's age when discussing seniority might be sensitive. 
The role requires an actor of a certain age for authenticity.
Pro Tip 3/3Not Always Negative
While it suggests aging, it doesn't necessarily imply anything negative about the person. 
She, being a woman of a certain age, brings vast experience to our team.