By Jesse Moeller
Answer: CHECKPOINT

This puzzle is a diagramless crossword, where all clues are presented in a single, undifferentiated list, with only a set of 10 context-free grammars mapping clues to grid entries. Solvers need to solve the clues and determine the mappings between clues and grid entries via the grammars.

Additionally, the grammars provide information to help fill out the grid. E.g. grammar S6 can be used to determine that the seven clues matching it are all 4 letter words starting with B, M, O, R, or T, helping to fill the grid even if the matching crossword clues have not been solved yet.

Once the grid has been solved, the final extraction is performed by finding locations where the clues matching a given grammar intersect themselves (one per grammar) and reading them out in S1–S10 order (which is also grid order). This gives the answer CHECKPOINT.

Filled grid with extracted letters highlighted:

S T R E G A
T M C T H E M E S A R M
O A R E E V E E S L E A
S L A T P O E L O B S
H I G H V O C A B P E S T
R E N L O A M S
E D S E L S O C O T I P
L I K E C R O S S E S L I K E
M A Y R E P O C O M E T
M O D A L S O Y
I O T A L U F T W A F F E
K N E X T O R L O O M
E A R R E H I R E N A M
A N N S A B O T S E L Y
S T O N E S

Crossword clue and grammar pairings:

S1
A donkey—ASS
Advice-giver Landers—ANN
Director Burton—TIM
Home chnl. of “Splatterday on Saturday”—TMC
Linguistic suffix—EME
Rocky cliff face—CRAG
Word preceding willikers—GEE
S2
DJs can spin them—LPS
It contains hooks and loops—VELCRO
Mel’s Mad motorer—MAX
Month named for a goddess of growth—MAY
Motifs—THEMES
Number of Magi—THREE
Teen drama that popularized Chrismukkah (2 words)—THEOC
S3
A young horse—FOAL
An annoying thing—PEST
Co. that created Game of ThronesHBO
Construction toy—KNEX
Soothing plant—ALOE
Stroke affectionately—PET
Television award—EMMY
Author of The RavenPOE
S4
A day in Madrid—DIA
A tool used when rowing—OAR
Anonymizing network software—TOR
Ingred. in a Scarlett O’Hara—SOCO
Manfred von Richthofen, for one—ACE
Supply with weapons—ARM
The very end of something—TIP
S5
Add to the payroll again—REHIRE
Air force of Nazi Germany—LUFTWAFFE
Common vegan protein source—SOY
It’s over your head—SKY
Jagger and bandmates, shortly—STONES
Part 1 of a helpful hint (3 words)—LIKECROSSESLIKE
Pokémon that evolve into 8 different types—EEVEES
S6
Comedian Daniel—TOSH
Empire of Mansa Musa Keita—MALI
Jeers—BOOS
Man smote for wasting seed—ONAN
October’s stone—OPAL
Pole found on a ship—MAST
Seabird related to skimmers—TERN
This kind of man takes your car away—REPO
Yanks’ counterparts—REBS
S7
Denoting the mood of a verb—MODAL
Consume food—EAT
Grassy meadow—LEA
Halley’s is one—COMET
Partner to nose and throat—EAR
Tosses gently—LOBS
True blue—LOYAL
What someone can do to your toes (2 words)—STEPON
S8
A minuscule amount—IOTA
Eisenhower, for short—IKE
It could contain a rapier or a flying shuttle—LOOM
Kingsmen member Jack—ELY
Nightmarish street—ELM
Soils containing both clay and sand—LOAMS
Where you might find a Sparsam or Dombås—IKEA
S9
Color associated with anger—RED
Grand Prix gov. body (2 words)—FONE
Part 2 of a helpful hint (2 words)—REVEALSSOLUTION
Stimpy’s pal—REN
What you do to the first syllable of syllable, for example—STRESS
Where McCain served, briefly—NAM
XML extension used by news feeds—RSS
S10
A logophile prob. has this (2 words)—HIGHVOCAB
Herbal liqueur colored with saffron—STREGA
Clogs formed from wood—SABOTS
Famous flop—EDSEL
Jet Matt that used to be a Bear—FORTE
Russian capital—MOSCOW
Thin strip of wood, as in a crib—SLAT