killing clover
 

Try adding a few drops of dish soap to the spray mix. I've heard that
clover can have an oily coating on the leaves.

Wait at least 2 weeks before expecting results.

Read up on clover lawns. I remember my father carefully considering
how much clover was to be added to the lawn seeds he was buying. Back
then you bought seed at a nursery and they would bag whatever mix you
wanted.
Clover lawns were desireable in certain settings.