Some electronic automatic transmissions (and you didn't say that this
was an automatic, but it is, isn't it?) have locking torque converters.
Under some conditions, as you slow down from the locked condition, just
before you come to a complete stop and the transmission speed drops
below the engine speed, the converter will unlock with a distinct
*clunk*. Typically this will happen only after you have driven at some
sustained speed for some time, then stopped without any other need for
the transmission to shift.

One other possibility, again with electronic transmissions, is that
they will downshift all-at-once at a near-stop especially if you tromp
it instead of coming to a full stop. That too will give a *clunk* and a
bit of a jerk as well.

Neither is a problem unless/until it happens all the time.

If this is a manual-transmission car, this "sounds" like a suspension
bushing is loose/worn/missing and/or a strut top bearing is worn. When
you stop, the vehicle goes 'nose down' and the suspension is thrown to
a different configuration than when moving. A piece going
metal-to-metal because the rubber bushing is gone would go *clunk*, or
if the needle bearing is worn in that angle, the top of the strut would
*clunk* on stopping.

This could be more serious and should be searched out and pin-pointed.
If you are in a panic situation and a tie-rod or ball joint or strut
fails... that could be very exciting and acutely embarrasing...
assuming you survive the experience.

Peter Wieck
Wyncote, PA