That in itself though suggests that he's not happy with 2 or 3 of what we presume is his current 1st choice XI. As you say, it looks like a quality CB to partner / bring McGahey on and again, a proven striker. As above, not sure what this says about Higdon and McNulty.
Well we know for a fact that he had lined up the signings of another right back (Freeman) and a pacy striker (Bennett).
Since that deal fell through, we haven't signed anyone for either of those positions so that accounts for 2 of the 3.
He's also on the record as saying that Pearce is a target or he might try and get Maguire back on loan.
So centre-back is clearly the third position he's trying to sign a player for.
Why does he want to sign players for those positions?
1) We only have one specialist right back and he prefers to play Davies further forward.
2) He was forced to sell Maguire and hasn't yet signed a suitable replacement. He didn't sign Collins who is 31 and hasn't yet received a new contract offer. McGahey is only 18 and isn't up to Maguire's level yet. Butler simply hasn't worked out.
3) None of our current four strikers (Higdon, McNulty, Baxter, Porter) has any pace. It's a vital weapon that we're currently missing.
So far, Clough has patiently built a squad consisting players available on free transfers or for small undisclosed fees. What he hasn't been able to sign are proven players who are under contract, playing well and will therefore need to be prised away from their current club.
I get the impression he's challenging the board to go to Leeds and Pearce (for example) and make them both a fair offer that they won't refuse. You know, like what most other clubs do.