Foster has been in prime form for Albion during his 18 months at the Hawthorns and feels his performance in the 2-0 win at Liverpool last week was the best of his career.
But he has never wavered from his decision to stop making himself available for his country just under two years ago when a Birmingham player.
Clarke said: "If you're looking at a top-line goalkeeper, every mistake is analysed. If you go with England, it's magnified 10 times.
"Ben decided he'd rather spend time with his family than be put under that stress and strain and we respect that. For us as a club, it's good.
"Ben likes to be out of the limelight. He likes to go out, do his training and play as well as he can for Albion.
"He gets enough satisfaction from that to keep his career going forward."