1: A supporter starting to mock President Garfield's middle name (5)
4: Drop in rent keeping me housed after last month (9)
9: Will addition show 100 + 0 + 500 + 99 + 49? (7)
11: Greek letter for the teaching assistant (5)
12: Irately blasted the way things are (7)
14: Exciting moment, actor as reviewer (11)
17: How to eat the heart of marsupial (3)
19: Think at length about lost planet, comet (11)
23: Be of use to a head covering, we hear (5)
24: Foolish old African dictator concerned with the ear (7)
26: Mobster at heart, presently I'll be carrying expensive pistol on hip (7)
27: Civil libertarian sends building uprights (4,5)
28: Priestess betrays Sen. Kefauver (5)