1: Down under - thoroughly (2,5)
2: He wrote a bit of poetry! (3)
3: One final, huge Greek goddess (3)
4: Short line in letter back-fires (5)
5: They keep servants (9)
6: A favourite car of Seattle natives. (11)
7: Girl hatches subterfuge in prison tower (11)
8: Running across obscene libation from the East Texas town? (7)
12: A properly run lottery might be a complete success (1,5,5)
13: One later enters, like, with matching sides (11)
16: Added twist used in job (9)
18: I'm getting old and you can't get over it (7)
21: Heart of delicatessen, certainly, is meat (7)
24: First Lady, archetypical matriarch, and cowgirl finally talk candidly (5)
27: Complain about the horse (3)
28: Child, bask by the sound (3)