1: In secrecy, cleverly adapt to new function (7)
2: Support a deranged original (11)
3: As trail meanders, they're useful to a cowboy (7)
4: Bird and man going different ways (9)
5: Revolves around a star. (3)
6: 'Observe!' I cry to the audience (7)
7: Sort of uninitiated cheat (3)
8: Sci-fi pioneer composes Mercury Sources (1.1.,5)
13: Playwright rethinking copyright wrangle (4,7)
16: Declares, 'Ann put on a bit of weight' (9)
18: Outfield swamps East team, scoring all the points (7)
19: Ring writers, each far from land (4,3)
20: Dope turned to eat bun, starting off big (7)
21: Revolver pointing up and down (7)
25: Odds of niece being born (3)
27: Residue has scattered (3)