Conversion uses all combinational logic

Tricky, thank you very much for all your help. I'm a student and I mostly do software.

Could I implement a multiplier as follows, and if I did would this only instantiate a single multiplier that I could use over and over via a state machine. So in state A, I input the operands, then in state B, I receive the processes output?

process(a,b,clk)
begin
if clk'event and clk='1' then
d<=a*b;
c<=d;
end if;
end process;