The West Brom boss has seen his options reduced by injury and international call-ups in the past month, while Goran Popov is now facing a three-match ban following his red card for spitting at Kyle Walker in Sunday's 1-0 defeat against Tottenham at the Hawthorns.
The main worry for Clarke surrounds key midfielder Youssouf Mulumbu, who has returned from the African Cup of Nations still struggling with the knee injury he was carrying before he left for the tournament.
George Thorne has suffered cruciate knee ligament damage and faces an eight-month lay-off while striker Peter Odemwingie was left out at the weekend following his failed transfer deadline day bid to join QPR.
Therefore, with players unattached to clubs still able to move outside of the transfer window, Clarke is set to look at bringing in reinforcements, although he played down talk of a move for Nigel Reo-Coker.
He told the club's website: "Youssouf missed the last game before he went to the African Cup of Nations because of an injury. He went, played three games, has come back and still has a problem with his knee. I've got to be honest, I'm not sure if it's a short-term or long-term injury."
Clarke added: "There are a number of free agents on the market now. I saw we were linked with him (Reo-Coker) and now we've lost another member of the squad it is something I might have to consider. Not specifically Nigel, but maybe we have to look just to see if we need to boost the squad a little bit."