The former Chelsea coach has also claimed that it would take "a fortune" for clubs to lure any of his key players away from the club.
Clarke told the Birmingham Mail: "It's difficult to speculate how many players will come because you don't know how many clubs are going to try to take some of your players.
"At the moment, looking at the squad, if we were to bring in three or four that would be enough - but things can change.
"Our players aren't going to be cheap. I don't think anyone would be wise to come for any of our players because they will cost a fortune."
The Baggies currently sit eighth in the Premier League table.