Ferrier, who told the Saddlers he wanted to leave earlier this summer, has signed at Prenton Park after the two clubs agreed an undisclosed fee.
His departure means Elijah Adebayo, Josh Gordon and Mitch Candlin are the only out and out centre-forwards currently at the club.
But Clarke guaranteed there will be two new strikers arriving before the transfer window closes on September 3.
"There will be two centre-forwards joining before the end of the window," the boss said.
"There is nothing more certain than that.
"It's about getting the right centre-forwards. I can pluck a centre-forward out from anywhere and bring him in tomorrow.
"But it's about getting the right centre-forwards. It is such a key area of the pitch.
"We have obviously lost a lot of goals out of the team with Cookie (Andy Cook) going and Morgan going as well.
"But we are doing a lot of work in the background to make sure the two we get are the right fit for the club and for the job at hand."
When the two new strikers do arrive, Clarke revealed he expects them to be part of the striker force that nets between 35 and 40 goals.
"Every manager you have got to take your chances, you have got to be clinical," he continued.
"I’m looking for my team to score goals from all areas of the pitch.
"But to be successful, you have got to try and get 35/40 goals out of your strike force.
"At the end of the window, we will have four strikers who have got to produce that.
"But the centre-backs, full-backs, wing-backs and wide players all have to be clinical in the final third."
Walsall rejected a bid for Ferrier – believed to be from Tranmere – earlier this summer.
But Clarke, who met with supporters at a focus meeting on Monday, was happy to sanction the move – with the boss adamant he won't keep hold of any player that doesn't want to be at the club.
"We have known for a while now that Morgan’s desire was to leave," the 41-year-old added.
“He made that clear in the first week we came back.
"But these things take time to develop. We’ll wish him all the best and thank him for his efforts.
“I have said it all along we want players who want to be at the football club. It’s the start of a new era, a new dawn.
“It’s a new group, a new owner and I know the fans – having spoken with them the other night – want players who want to be here."