The 34-year old French striker has joined the Baggies on a one-year deal and Clarke is looking forward to again working with the classy hitman after they spent time together at Chelsea back in 2008.
"We are missing a bit of firepower from last year - we're trying to put that right - and to kick off with the signing of Nicolas at the start of the summer is a great boost," Clarke told the club's official website.
"The more quality players you can bring to the club the better - and no-one can question Nicolas' quality.
"He's a player I have worked with before as I was at Chelsea when they signed him. He's got a great work ethic, looks after himself and is a consummate professional.
"If you add that to the obvious talent he's got I think he can prove to be a really top signing for the club.
"His experience with some of the top clubs in England and Europe will stand the group in good stead.
"Hopefully he will be able to inspire the other players to even greater heights than we managed to achieve last year."