Double Play. I'll start today with the unifier, which is very self-explanatory.
55-Across. Canoeing challenge whose first word can precede the start and whose second word can precede the end of the answers to starred clues: WHITE WATER.
55-Across. Canoeing challenge whose first word can precede the start and whose second word can precede the end of the answers to starred clues: WHITE WATER.
20-Across. * Fruity adult beverage: WINE COOLER. We get White Wine and Water Cooler. A Wine Cooler can be either a special refrigeration unit for storing wine or a carbonated beverage of wine and fruit juice.
White Wine
Wine Cooler
28-Across. * Black-spotted orange flower: TIGER LILY. We get White Tiger and Water Lily.
White Tiger
Claude Monet's Water Lilies
38-Across. * Toy pistols used on stage: CAP GUNS. We get White Cap and Water Gun.
White Caps on the Ocean
Water Gun, also known as a Squirt Gun.
White HOT!
Water Wheel
Across:
1. Chinese sauce additive: MSG. As in MonoSodium Glutamate.
4. Olympic swimming star Ledecky: KATIE. Katie Ledecky (née Kathleen Genevieve Ledecky; b. Mar. 17, 1997), has won 5 Olympic gold medals and 15 world championship gold metals.
9. L.L.Bean competitor: J.CREW.
15. Stereotypical Pi Day celebrants: NERDS.
17. Handel's "Messiah" et al.: ORATORIOS. An Oratorio is similar to an Opera. Oratorios became popular in the 1600s and 1700s because the Church forbid theatrical performances. Thus oratorios were musical compositions with an orchestra, a chorus and generally a soloist, but without the costuming and theater props. Oratorios also tended to focus on religious topics.
19. Creepy film motel: BATES.
22. Put in the mail: SENT.
23. Cowboys QB Prescott: DAK. Dak Prescott (né Rayne Dakota Prescott; b. July 29, 1993), was born in Sulphur, Louisiana. The Cowboys lost to the Bears last week.
26. "Keystone" police: KOPS.
34. __ Valley: Reagan Library site: SIMI.
35. Strand at a ski lodge, say: ICE IN.
37. Pitcher's stat: ERA. As in Earned Run Average.
41. Prefix with natal: NEO-. As in Neonatal, which refers to newborn babies.
44. Novelist Leon: URIS. Leon Uris (né Leon Marcus Uris; Aug. 3, 1924 ~ June 21, 2003) is probably best known for his 1958 novel Exodus, which is about the creation of the State of Israel.
45. They, to Thierry: ILS. Today's French lesson.
49. Artist Warhol: ANDY. Andy Warhol (né Andrew Warhola; Aug. 6, 1928 ~ Feb. 22, 1987) died at age 58 from complications of gall bladder surgery. In 1968, an assassination attempt was made on his life in which he was seriously wounded.
50. "The Good Earth" mother: OLAN. The Good Earth is a 1931 novel by Pearl S. Buck (née Pearl Sydenstricker; June 26, 1892 ~ Mar. 6, 1973) about family life in China in the early 20th Century. It is well worth reading.
51. Some SAT takers: SRs. As in Seniors in High School.
52. Olympian bigwig: ZEUS. Oh, as in the Greek god of the sky and thunder, not the Olympic games.
65. Not tight enough: LOOSE.
66. ER VIPs: MDs. Medical Doctors are the VIPs in the Emergency Room, but don't forget about the ER nurses, who also play an important role.
67. Cockamamie: INANE.
68. Beginning: ONSET.
Down:
1. Cat's cry: MEOW.
2. Indian cover-up: SARI.
4. Rap on the door: KNOCK.
5. Sleek, in car talk: AERO.
6. 75% of a quartet: TRIO.
8. Ancient mystic: ESSENE. The Essenes were a Jewish sect from about 200 to 1 BCE. They are considered to be the authors of the Dead Sea Scrolls.
9. Position at work: JOB.
10. Enduring work: CLASSIC.
11. Baptism or bris: RITE.
12. Like Olympic years, numerically: EVEN.
21. 1921 play that introduced the word "robot": R.U.R. This play appears with some frequency in the crosswords. It is a 1920 play by Czech writer Karel Čapek (Jan. 9, 1890 ~ Dec. 25, 1938). R.U.R stands for Rossumovi Univerzáiní Robots (Rossum’s Universal Robots). The play takes place in a factory that makes organic, artificial people called as Robots. These Robots, however, were more like human people rather than the current concept of robots.
26. Stay fresh in the fridge: KEEP.
27. Celeb with her "OWN" network: OPRAH.
29. Little rascal: IMP.
30. Lively baroque dance: GIGUE.
36. Prone to prying: NOSY.
39. Often-bookmarked address, briefly: URL. As in the Uniform Resource Locator.
40. Grafton's "__ for Noose": N IS. Sue Grafton (Apr. 24, 1940 ~ Dec. 28, 2017) wrote a series of crime novels, each beginning with a letter of the Alphabet. The first in the series was A is for Alibi. She wrote all the way through the letter Y (Y is for Yesterday). Sadly, she died before she could begin what would have been the final book in the series, Z is for Zero.
43. "80's Ladies" country singer: K.T. OSLIN. I am not familiar with K. T. Olsin (née Kay Toinette Olsin; b. May 15, 1942).
47. "Yee-__!": HAW.
48. Surround, as with a saintly glow: ENHALO. Yup. It's a real word.
51. "Ni-i-ice!": SWEET!
52. Cube root of acht: ZWEI. German math.
53. Merit: EARN.
56. Part of, plotwise: IN ON.
57. Boxing ref's calls: TKOs. As in Technical Knock Outs. A crossword staple
58. "Anything __?": ELSE.
59. Opposite of exo-: ENDO-.