Clovers are a pioneer group of species, which colonizes bare ground, like many weedy
volunteer species, and establishes a system, but seldom grows by itself for long. The purpose of all that nitrogen is to
feed other plants and establish a succession which might include clover, but will no doubt be advantaged by other nitrogen loving plants.
You are right that the clover does fix it's own nitrogen (or to be more exact, the bacteria rhizobia which has a symbiotic association with the clover fixes atmospheric nitrogen making it available to the clover plant
and to the soil around the clover roots). The soil that has been enriched by the rhizobia becomes available to the feeder roots of neighboring plants, even before the clover roots start dying (which happens more often than you might think). The clover provides a dense ground cover, which creates a humid soil surface where other seeds can germinate. Regardless of what you do, the clover will nurse and feed the volunteer aggressors, and they will want to be there.
My suggestion: Definitely enrich and mulch your soil as best you can with leaves or whatever you can get, but I wouldn't mix it with the soil; My rule of thumb is always mulch (add carbon) from the top/never mix it with your growing soil.
In additiion to mulching, what you could do is plant some other plant(s) seeds with the clover, so that when the clover establishes and starts to give off it's nitrogen, the plants that will benefit will be the one (or many) that you plant with it.