Jup, there's no problem with driving it normal if it's only the top mount.
But if the mounts are loose, the clonk should repeat more often when driving.
Next to Trees tip you could try pushing the engine back/down into the car by hand, if everything feels firm, the mounts could still be fine.
It could also be the ABS/ESC selftest.
My twingo RS had this when starting from cold and doing a bit more than walking speed and I noticed it on my clio sometimes.
It's only one short clonk from under your feet.
This also appears if you drive slower after you had a harsh brake and the ABS had to step in.