1: Bio class setting

4: Diamond defect

8: Neuter, as a horse

12: Scrabble letter

13: Ness, for one

14: Snobbishly unfriendly

16: Golfer Irwin

17: Time past

18: Ball bigwig

19: Unsuitable

21: Sew up

23: Campbell of country music

24: Vote to kill

25: Rushes

27: Piano man Charles

29: Be flexible

30: Grass in a loft

31: Unit of oil production, briefly

34: Axis foes

37: Identical

38: 'Sweet Pea' singer Tommy

39: Joint inflammation

40: Go, with 'on down'

41: Vampire's tooth

42: Coat of many colors?

43: 'Flee, feline!'

45: Treats vengefully

47: Bearded African grazer

48: Pivotal

49: Gravy server

50: Ebay posting

51: Crooked

52: Goalie's protection

55: Lay macadam

58: Multigenerational story

60: Germ cell

62: Puts out

64: Nearly closed

66: Knocks for a loop

67: Bullriding venue

68: Major ___

69: Wood used for furniture

70: Sushi wrap

71: Fat on the bird feeder

72: 9 - 5, e.g.

1: Jungle vine

2: Put to rest

3: Answering-machine sound

4: Take wing

5: Appeared, in a threatening way

6: Lots, sometimes

7: 'At what time?'

8: Debatable gift

9: Pensive piece of poetry

10: Take it easy

11: Loser to Clinton in '96

12: Word after paper or before skinned

15: Marsh

20: Quaker's address

22: Spot of brandy

26: November winners

28: Bluto's assent

29: Byte fraction

30: Come to pass

31: Spoiled child

32: Fibula or femur

33: Table supports

34: Bug-eyed

35: Filet mignon source

36: Pip

37: Barfly

40: Cargo compartment

41: Like a fiddle?

43: Biathlon need

44: Give up

45: George W. Bush, to George H.W. Bush

46: Butter units

49: Turned into

50: Kind of nut in 'South Pacific'

51: Dainty ornament

52: Word with cord or chord

53: Geometry calculations

54: Kind of calendar

55: A pop

56: All over the place

57: __ infra: see below

59: Hippies' homes

61: Course of action

63: Absorb, with 'up'

65: Nonsense