3947 King by Rebel

Gregson considered this to be an excellent puzzle with an original concept. The preamble told us that the grid was a representation of the title of a novel. When solvers had completed the GROUND EAST and SOUTH clues it was possible to see AMERICA and THE TRIAL, two works by Franz Kafka. Extra letters gave the message AUTHOR AND TWO OTHER OF HIS NOVELS – ENTER TOPMOSTLETTERS. The Central Region clues gave answers that had to be entered in a third dimension creating a castle with five levels rising above the grid. When the topmost letters were entered the name of FRANZ KAFKA appeared almost magically!
The title referred to K, the central character in The Castle.

 
GROUND EAST
1 Hall's side altered atmosphere (4)
AURA aula (hall) change L (left) to R (right)
4 Rap crime reform, part of carrot perhaps? (8)
MERICARP anag. rap crime
9 Storehouse with new opening is plant again (5)
REPOT depot with new first letter
10 International body throwing out ounces (6)
UNESCO anag. ounces
13 Will's rapier thrust (4)
TUCK 2 definitions
14 I'm back inside house with chimney, No 67? (7)
HOLMIUM I’M rev. in HO (house) + LUM defined by its atomic number.
15 Ogre's eaten one - scream! (6)
SHRIEK I in SHREK the cartoon ogre
20 Card table enclosure all set - East opening (5)
TEASE (to card) T(abl)E + A + S + E
22 Bad optician's lists might make Caitlin's eye droop (6)
PTOSIS comp. anag. optician’s lists less letters of Caitlin’s
25 Sort of mineral found in crushed core of acid deposits (8)
DIOPSIDE anag. central letters AC(ID DEPOSI)TS
28 Judge worth of strongest. I'm at ease partly (8)
ESTIMATE Hidden
34 Male hawk wheeling around rat by large tree (6)
TARSAL RAT re. + SAL
36 Magnolia you'll paint regularly (5)
YULAN odd letters
41 That's beginning sin - Adam's first new earthling (6)
TERRAN T (initial of That) + ERR + A + N (new)
44 Evil gale blowing inside is not allowed (7)
ILLEGAL ILL (evil) + anag. GALE
45 Square slate bridge (4)
SPAN S (square) + PAN (criticise harshly)
46 Indirect efforts since 13th November for instance (6)
ASIDES AS + IDES
47 Tiniest slate broken (5)
LEAST anag.
48 Beats victims drawn in, they're suckers (8)
LAMPREYS PREY in LAMS
49 Measure cost and time (4)
FEET FEE + T

GROUND SOUTH Extra letters are shown in square brackets.
1 A national embracing tax in rare instance of opposition (8)
ANTITHET TITHE (tax) in A N[A]T
2 Uruguay employs wild oxen (6)
URUSES UR[U] + USES
3 Sickening strain perhaps drawing map again (7)
RECHART RE[T]CH + ART (drawing)
4 Rich male, he takes on single daughter (6)
MONIED ON + I in  (M (male) + [H]E) + D
5 Heavenly river swallows other one left (8)
ETHERIAL [O]THER + I in EA + L
6 Entrance - fairy dance not good (5)
INLET [R]INGLET less G
7 Conglomeration of countries: America, Australia, part of New Zealand, Austria (4)
ASIA [A] America + A (Australia) +SI (South Island) + A (Austria)
8 King's orb's power and portent (4)
POME P + OME[N]
11 Moss bed ill-suited for stud (6)
EMBOSS anag. MOSS BE[D]
12 Wounded I would skirt round page boy with bow and arrow (5)
CUPID P (page) in CU[T] + I’D
22 I've got fat parrot consuming weight to live (8)
POT-BELLY [W]T + BE in POLLY
23 What can catch plenty at sea, none see it (8, two words)
SEINE NET anag. N[O]NE SEE IT
24 Free periods produced awful racket (6)
RISPED anag. PERI[O]DS
27 Sliding in up to recess (7)
ILLAPSE [T]ILL + APSE
29 Address on board ships (5)
SAILS [H]AIL in SS
31 Look at uneven rise to high places (6)
EYRIES EY[E} + anag. RISE
33 Woolly llama's extremities decorated bar the top (6)
LANATE LA (extremities of LlamA) + O[R]NATE less O
35 Nasty orange inflammation locally (5)
ANGER anag. [O]RANGE
37 Man Friday first to find old coin (4)
RIAL [F]RI + AL (a man)
38 I'm hot after stroll, losing bulk to become thin (4)
SLIM SL (extremities of STROLL) +I’M [H] hot

CENTRAL REGION
GU16 Upset I l[i]ed or stirred up (6)
ROILED anag.
GU19 Patterned fabric, ornamental clasps lacking zip (6)
BROCHÉ BROOCHE[S] less O (zip = zero)
GU39 Big belly from pa[n]cake lunch old fool left out (6)
PAUNCH Hidden less CAKE (old fool) and L
GU43 Circular badge, strip of cloth - he drew it (6)
RONDEL RO[O]N + DEL (delineavit = he drew it)
GUSE16 Piteous vulture mauled fellow in no time (6)
RUEFUL F (fellow) in anag. [V]ULTURE less T
GUSW19 Split in half sombre pain (6)
BREACH (SOM)BRE + ACH[E]
GUNE39 Punch humourless relative (6)
POUNCE PO (humourless) + UNC[L]E
GUNW43 He's wise ruler, Lord San in disarray (6)
RONALD The name means wise ruler. anag LORD [S]AN
1E16 S[e]wing central foil cut round windows (5)
OCULI  anag. OILCU (centre of foil cut)
1E40 Hen will love greeting (5)
HELLO HE[N]’LL + O
1S19 Valued tat in rubbish (5)
RATED [T]AT in RED
1S21 Match [e]very letter thanks (5)
VESTA V (very) + ES + TA
2E24 Stop rescue[r]s reportedly (6)
FREEZE sounds like FREES
2E30 US whitewashes ruined ro[t]und knight's son (6)
SKUNKS To skunk =
 to defeat without allowing to score. (US)  K in SUNK + S
2S17 Local's way out? [H]is stabling yard (6)
SMEUSE S (is) + MEUSE (see MEWS)
2S18 D[e]rive a meeting place (6)
AVENUE A + VENUE
3SE16 Meadow nourished as a luxuriant bel[t]? (6)
LEAFED LEA + FED like a bel tree
3NE39 Awful acne [o]n one - it's to do with adolescence (6)
NEANIC anag. acne + N + I
4E16 Haggled [p]rice is fine (4)
ERIC anag. RICE
4E41 Goggle ga[m]e contains unknown factor (4)
GAZE Z in GAE
4S19 B[o]eing's chopped fabulous flyer (4)
HUMA (a phoenix) HUMA(N)
4S24 Plod[s] left in command by force (4)
FLIC F (force) + L + IC
4D17 Is petition for s[t]eed (5)
ISSUE IS SUE
4D18 Soft rock, bo[l]d for Gypsy King (5)
CHALK CHAL + K
4D24 Scot's flute with end on fir[e] (5)
FIFER F + (CON)IFER
4D26 Balances mean[t] assets halved (5)

MEETS half letters of ME(AN) (ASS)ETS
4D30 Flavoured drink: girl has i[t] (5)
LASSI LASS + I
4D32 Judge cut[e] fools (5)
ASSES ASSES(S)
4D41 [R]egret inept salute (5)
GREET anag.
4D42 Some clergyman elegantly anoint[s] (5)
ANELE Hidden