1: One-time philosophical teaching turned him to classics (13)

9: True side (5)

10: Stupid alien filmed in undergrowth (7)

11: Grave study: code-breaking? (13)

12: Schoolchildren made to come back on Saturday make mistakes (4-3)

14: Later round without an opponent (3)

16: Taverns quoted cool clique (3)

17: One may be transported by this kiss, it's said (3)

18: How to get around doing business, essentially (3)

19: More pronounced rasp (7)

21: Like a high ranking diplomat's awful ambrosia salad (13)

25: Fighter to join around fourth of April (7)

26: Symbol to recognize (5)

27: Changes direction with care, as befits a benefactor. (4, 4, 5)

1: Bugs going after quiet gags (7)

2: Virago would dwell on male chromosome (5)

3: Delicate stem is enlightening (5,4)

4: Snarling assistant to devil worshipers (9)

5: Pound off top of door--what's inside? (5)

6: Skier's heart rivals climbers (5)

7: It's expedient to engage in habit-forming activity (9)

8: Gets bastion rebuilt (7)

13: Lined salt shaker made ready for use (9)

14: Huge military display made a large, indelible mark. (3, 6)

15: Sounds like I hit it into orbit (3,6)

17: Eat or drink after the dollar improves (5,2)

20: Awfully servile experiences again (7)

22: Second go as a spouse (5)

23: Quiet floor decoration is a sign of indifference (5)

24: Private dinner starts late (5)