Across1 Underground areas explored by spelunkers

6 Car-buying necessity, for many

10 Degs. for some entrepreneurs

14 Stuffy “Me too”

15 Competent

16 Noble rank above viscount

17 Stuck in the muck

18 French champagne brand

19 “Well, would you look at that!”

20 Make a polite visit

23 “__ whiz!”

24 Runs easily with long strides

27 False start punishment, in football

34 County Clare’s nat.

35 Internet letters

36 “The Banana Boat Song” opener

37 Trails behind

39 Color TV pioneer

40 “Barbie” actor Liu

41 La __: Real Madrid’s division

42 Frank on the grill

45 Naught

46 Incredibly hard to hold

49 Photo app filter shade

50 Time period often named for a monarch

51 Celebratory shout heard before “Auld Lang Syne” is played, and an apt title for this puzzle?

58 Crèche trio

61 Moisturizer brand

62 Missouri River tributary

63 Minnesota representative Ilhan

64 Junction point

65 Spoke wildly

66 Sheepherding pig in a 1995 film

67 Smack

68 Austin Powers player Mike

Down1 Training __: NFL preseason practice time

2 Tibet’s continent

3 “Your mileage may __”

4 Come to light

5 Judgmental glance

6 Bedside light

7 Double-reed woodwind

8 Actor Guinness

9 Invasive plants with stinging hairs

10 Note-worthy purchases?

11 Green __, Wisconsin

12 Escort’s offering

13 Devious

21 Tailor’s line of stitches

22 Freight weight

25 “Seinfeld” character who worked for Pendant Publishing

26 Really frustrate

27 Jam-packs

28 Vowel-shaped track segments

29 Carrot or celery, informally

30 Not so common

31 Hazardous

32 Initial strategy

33 “__ be sorry!”

38 Blue gem

42 Some cards in the board game Clue

43 “Now it’s clear!”

44 Overly catchy song

47 Actress Zadora

48 Come out against

52 Furrow former

53 When tripled, phrase spoken by 25-Down

54 No, in Russian

55 Icicle site

56 Ripening agent

57 Cincinnati MLB team

58 Unruly crowd

59 GP’s gp.

60 Chitchat