Gera is training again after his recovery from a second serious knee injury, but Clarke has insisted that the 34-year-old is still a month away from a return with the first team.
The 50-year-old told the Birmingham Mail: "Zolly is training, which is fantastic. He's doing well but I'm having to slow him down.
"He's very forward but he needs to relax – he's showing great enthusiasm but he's not match ready.
"It could be the start of October. We want a good four weeks of training before he's ready."
The Hungary captain has made just 18 appearances since his return to The Hawthorns in 2011.