Learning about multipliers, confused about cycles in relation to Wallace tree
A Wallace tree is basically a whole bunch of adders hooked up in series. If the inputs are entered by a clock edge (one cycle), no more clocks are needed until the complete output is read, so it only takes one cycle.

Of course, the cycle period must be long enough to allow the computations to propagate through the tree, and in the early days of microprocessors, adders were slow enough that a multiply operation could take several clock cycles. But the intermediate clocks were not applied to the multiplier, it was just a way of allowing the process to complete.