The Baggies goalkeeper recently made himself available for selection, having withdrawn from contention two years ago, citing niggling injuries and family reasons.
But his outstanding form for a West Brom side pushing for the UEFA Europa League places has seen him rewarded with a place in Roy Hodgson's squad for forthcoming World Cup qualifiers against San Marino and Montenegro.
"We're all delighted for Ben," said Clarke. "He obviously made himself available for selection and he explained his reasons for pulling out initially.
"It's good. I like my players to be involved for their countries because I think it's a great honour.
"We think, touch wood, that Ben is in a good place physically now. I'm sure he'll do well."
Foster won the last of his five England caps against France in November 2010 and Hodgson is delighted he will provide competition for Joe Hart.
"In our opinion we now have two excellent goalkeepers," Hodgson said at a press conference to name his squad for the double-header.
"Ben is in excellent form and it's good that after a long absence he's decided he wants to play again. I'm looking forward to working with him."