Solution to 12A has been deliberately left unsolved and is to be answered only by a non-regular / novice commenter, with proper annotation. Those who have answered earlier in the week, please give others a chance.
Someone to identify the theme and the theme words.
ACROSS
1 "Fabric is certainly from Germany" — king, maybe while clothing queen (8) JACQUARD {JA}{C{QU}ARD}
6 After backing explosive claims, Gujarat's leader has a problem (6) ENIGMA {M{Gu...t}INE<=}{A}
9 Recess on the counter in office space (4) APSE [T<=]
10 Article with murky origins leads to speculation (10) THEORISING {THE}{ORIGINS*}
11 Desperately tries to chase married man (6) MISTER {TRIES}*<=>{M}
12 Garbage recycled, say, after moving to small waste bins (8) A?H?R?Y?
13 Dr. X's Y? That's it! (3,2,5) END OF STORY {Y is end of story)
15 Hollow, easily forgotten past promise (4) BOND BONeD
17 Labour blocks its second candidate's aspiration (4) SEAT SwEAT
18 Get rid of water, honey, urn, myrrh (items devotees originally used during worship) (10) DEHUMIDIFY {Ho..y}{Urn}{My..h}{It..s}{De...s} in {DEIFY}
20 Korean vote surprisingly expresses no new change in leadership (8) TAKEOVER {KOREAn+VoTE}*
22 Warden and Woburn, for example, getting bowled for fifty twice in back streets (6) ABBEYS A(-ll+bb)BBEYS
24 Engineer random changes in parent note (10) MEMORANDUM {E}{RANDOM*} in {MUM}
27 Go through dessert, skipping one staple food item (6) PIERCE {PIE}{RiCE}
28 Screamed after suppressing a cry of anguish and turned pale (8) YELLOWED {YELL{OW}ED}
DOWN
2 Can I mash in fruit blender? (9) APPLIANCE {CAN+I}* in {APPLE}
3 Seeking technique studied secretly (5) QUEST [T]
4 Habits of extremely affluent bores (7) ATTIRES {Af...nT}{TIRES}
5 Prescribed food, not timepass! (3) DIE DIEt
6 Sensual and without reservations when out of India, husband moves lower (7) EARTHLY (-h)EART(+h)HiLY
7 "Angry Birds" — nice, impressively written (9) INSCRIBED*
8 Penny perhaps king's taken from fool (5) MONEY MONkEY
12 A different one, found in America, not here (7) ANOTHER [T]
14 Regularly worn hot Nehru cap of officials (2,3,4) ON THE HOUR {HOT+NEHRU+Of...s}*
16 New gas masks gain approval for military manoeuvre (2-3,4) NO FLY ZONE {N}{O{FLY}ZONE}
18 Married woman had to stray (7) DEVIATE {DEVI}{ATE}
21 Asian jazz genre — it's covered frequently (5) AZERI {jAzZ+gEnRe+It}
23 A couple of slices of bread, and eggs over well done (5) BRAVO {BRead}{OVA<=}
25 Period and comma, say, basically? (3) DAY Tail acrostic
Reference List
Certainly in German = JA, Queen = QU, Married = M, Easily = E, Bowled = B, Fifty = L, Engineer = E, India = I, Husband = H, King = K, New = N, Month = M