The idea that small changes can lead to vastly different outcomes, aka this effect, causes quite a "flap" among mathematicians
Butterfly Effect
Regarding this founder of the Holy Roman Empire, analysis of his left tibia shows he was "very tall, but not robust"
Charlemagne
A month of the year, or majestically grand
August
This Lady Gaga song says, "Play the cards with spades to start"--which, come to think of it, sounds more like bridge
Poker Face
A chef named Ignacio in Piedras Negras, Mexico is said to have lent his nickname to this dish using tortilla chips
Nachos
Total traffic jam
(8 letters)
Gridlock
These rodents, genus Cynomys, weigh just 2 to 4 pounds but are pivotal to the grasslands; their digging aerates & fertilizes the soil
Prairie Dogs
This 6'3" president loomed large in every way; to Tom Wicker, he "seems 20 feet tall--when he really measures no more than 10"
LBJ
A native of a part of the Czech Republic, or an eccentric art lover who's not into social conventions
Bohemian
"I know she'll be the death of me / At least we'll both be numb", sang The Weeknd in this chart-toppe
Can't Feel My Face
This type of internal combustion engine was named for a German guy with the first name of Rudolf
Diesel
Specs
(7 letters)
Glasses
n Jewish mysticism, a "little ring" sent by God to this biblical king enabled him to control demons & speak with animals
King Solomon
The tallest current world leader is former basketball player Edi Rama, now a resident of Tirana & the 6'7" prime minister of this country

Albania
The Roman god version of FedEx, or a chemical element
Mercury
The classic musical "Bye Bye Birdie" gave us the song that says, "Gray skies are gonna clear up", so do this
Put on a happy face
In 4-letter figure skating jumps, the Axel is from a skater's first name & this one was originally a last name
Lutz
Early record player
(10 letters)
Gramophone
Thanks to this 2-word financial term that produces exponential growth, even a small sum of money can eventually grow into a fortune
Compounding Interest
This czar-turned-emperor was of "enormous height" & "unusual physical strength"; no wonder Catherine I swiped right
Peter the Great
Relating to the biblical sea-parting guy, or a decoration using tiles to form patterns
Mosaic
Adele did this amazing title thing & "watched it pour as I touched your face"
Set fire to the rain
From the name of an Old Testament patriarch, this adjective refers collectively to Judaism, Christianity & Islam
Abrahamic
A slug or snail, by class
(9 letters)
Gastropod
A single gram of the 210 isotope of this, the most radioactive naturally occurring element, could kill 50 million people--yikes
Polonium
A queen at 6 days old, this daughter of James V was a foot taller than average for her time: 5'11" while she still had a head
Mary, Queen of Scotts
A Euro auto brand, or an official decree from a royal
Fiat
The Faces were early '70s stars with future Rolling Stone Ron Wood on guitar & this soon-to-be solo superstar on lead vocals

Rod Stewart
Named for a Paris professor of medicine, this syndrome causes numbness due to cold or stress
Raynaud
Chief ore from which to get the lead out
(6 letters)
Galena