1: Observed no Knight (5)
4: A muskmelon or cola nut pa sliced (9)
9: Crooked Nile ran on, just not in a straight line (9)
10: Manipulated Cleo, queen with a silver tongue (9)
12: Raced around a tree (5)
13: Sharpen search, including gym and cubbyholes (9)
15: He is found in the alloy described (5)
17: Wants - in fact, just has to have (5)
18: Drink to the crashing of beetle car (9)
21: Keep an eye on a new teak floor (4,5)
24: Development of GEHQ (9)
25: In Howard's End - one has a passage here from Forster (5)
27: Crooner Mel: famous, loveless, suffering (9)
28: Lacking energy, no Tech win (5)