John Rumm wrote:

With no clearance hole I cannot see how a screw can pull two pieces
together.

You can do it by brute force - just keep driving so that you strip
the thread created in the top bit of wood - then they will pull
together.

Or, slightly more subtly, drive the screw through the top piece into
the lower, then back it out of the lower one, pull the two bits tight
together, and drive again. More of a faff to describe than to do (at
least with a power driver) and tight enough for most purposes.

--
John