Puzzle

 ACROSS

  1 Experiment setting

  4 Mastercard alternative

  8 Gives a PG-13 to, say

 13 Columbia or Brown

 14 Holy ___ Empire

 15 Event notification that saves a stamp

 16 Ellipsis, informally

 18 Pagan religion

 19 Affectionate nickname

 20 Slap

 22 Nicki who has a feud with Cardi B

 24 Astrological ram

 26 Doorbell prank

 29 Bacteria behind many recalls

 31 Chow chow chow maker

 32 Verb commonly confused with "lay"

 33 Toy with an "Elevator" trick

 34 December letter recipient

 36 Sec

 37 Prefix hidden in "wildlife conservation"

 38 Founder of Pittsburgh's state

 39 "Enough!"

 40 Not just a challenge

 44 Really bothered

 45 Twisted water out of

 46 Capital north of Ho Chi Minh City

 48 Removes from a hose reel

 52 Pigs

 54 Dramatic sound effect

 56 Take responsibility for something

 57 Many times

 58 Superstar's attitude problem

 59 "Eek!"

 60 Not prove victorious

 61 Fix a rip

DOWN

  1 Many twist off

  2 Swear

  3 Tiny fraction of a modern hard drive

  4 November civic duty

  5 "This is SO bad for me!"

  6 ___ Paulo

  7 Picnic invaders

  8 Loyalty program perks

  9 Swedish DJ who sang "Wake Me Up"

 10 Picture file?

 11 List-shortening abbr.

 12 Sizable body of water

 14 Spiral-shaped pasta

 17 Venus statue's missing parts?

 21 Molten rock

 23 "Become a member today!"

 25 Space series genre

 26 Start of a request for an opinion

 27 Met's D.C. rival

 28 Weightiness

 29 Scrutinized

 30 Warming winter drink

 34 Take care of

 35 "Surely there's more to the story?"

 36 Insider's lingo

 38 Solar system octet

 39 Popular spring break destination in Mexico

 41 ___ Babies

 42 Sounds of exertion

 43 "Crocodile ___" (1986 film)

 47 Worshipped figure

 49 Infamous time of March

 50 Olympics sled

 51 Winter fort material

 52 Tofu base

 53 1914-18 conflict, for short

 55 Roswell sighting

Solution