Clover and timothy do very well when mowed, while most weeds do not. By mowing the pasture, you will really help out both. The reason the clover is now dominant in the pasture is because the timothy, which may have previously dominated, has consumed most of the available nitrogen in the soil, as all grasses including corn will do. This makes it tough on the timothy (which needs nitrogen to do well) and good for the clover (makes its own nitrogen). In a few years, expect this balance to turn. As the clover builds up the available nitrogen in the soil, the timothy will again begin to dominate. Simply mowing that pasture and leaving the clippings lay will alow it to remain strong for a long time. With heavy grazing or hay removal, fertilizer will have to be added to make up for what is taken away. The only reason not to mow clover is if you are in drought conditions which is quite the opposite of the soggy weather you have this year. Otherwise, not mowing will allow weeds to take over the pasture. I am not a horse guy but me and (4) previous generations of my family have grown clover to feed cattle, deer, and corn on a farm near your location since the Civil War days. Sometimes I let my nieghbors (horse folks) bale some of my fields when the timothy gets dominant and they would much rather have that timothy hay than clover. They act like clover may be harmfull to thier animals, is that true?