Clarke was already without Youssouf Mulumbu - on African Nations Cup duty with the Democratic Republic of Congo - and hamstring victim Claudio Yacob, while Graham Dorrans wants to leave the Hawthorns.
Now Gera's absence for a period of between six and nine months with a ruptured anterior cruciate ligament, might mean Clarke having to go back on his preferred option of keeping faith with his current squad.
Gera injured his left knee during Saturday's FA Cup tie with QPR at Loftus Road and scans have revealed the extent of the damage.
The 33-year-old sustained a similar injury in November 2011, which sidelined him for the remainder of last season.
Gera is scheduled to undergo surgery to repair his knee next week with the usual rehab time for this injury being six to nine months.
Clarke has challenged former Fulham player Gera to recover from this latest blow.
He told Albion's official website: "I'm devastated for Zoltan. He's a terrific guy and professional and I want to thank him for his contribution this season. It has been invaluable.
"He'll now get our full support during the rehab process.
"Zoltan has already proven he can come back from this injury once and produce at the highest level and I have no doubts he will do so again."
Gera has played a major part in Albion's fine form during the opening half of the season, which has seen them sustain a spot in the top half of the Barclays Premier League table.
He has netted four goals and also returned to international action with Hungary.
But now another lengthy recovery period lies ahead for the player who spent four seasons at Albion in his initial spell before rejoining from Fulham during the summer of 2011.