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.