You can cut clover anytime except in a drought. If you can't rake off the clippings I would suggest cutting no more than 1/4 of the height at a time to decrease the chance of the clover hay matting and suffocating the plants below. You can also be successful with herbicides like Vantage and Arrest herbicides. My experience is with the Arrest and it worked like a charm but if the grass is under the clover canopy you'll need to top the clover to expose the grass to the spray.