What to do about an excess of clover ? I have one area of a lawn where the
clover is taking over from the grass.

I can't imagine having an excess of clover.

Test the pH of the area to determine if it is unfriendly to grass. If it
is, adjust the pH.

If you REALLY want to get rid of the clover, you can weed wack it to the
ground and reseed to increase the grass population (won't get rid of it, but
should help to balance it out), dig the area out completely, use chemicals
(I do NOT like recommending chemicals) or get a pet rabbit and let 'im loose
in the yard every few days.

James