Now got almost all of S corners and most but nor all of NW and NE (2 6 letter words missing here. I don't believe *CK*u*)
Have only 2 clues to solve in the cloverleaf, but they only add up to 15 letters and have 27 letter spaces. Something to do with the central traffic sign no doubt; but I have looked at pages of US traffic signs! Ah well, I expect light will dawn.