Solution to 1A 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.
Open for anyone to solve, if not solved by 1 PM.
ACROSS
1 This formula was epic! Swear...amazing! (6) R?C?P? (Addendum - RECIPE {RECIPE+WAS}*={EPIC+SWEAR} [CA] - See comments)
4 A hit is humbling (8) ABASHING {A}{BASHING}
9 Dry a wet Roan, tied on and off (6) AERATE {A+wEt+RoAn+TiEd}
10 Husband with irritation about boundless love leading to spiritual awakening? (8) HANGOVER {H}{ANG{lOVe}ER}
12 It's a trivial sum, we hear to former Vice-President (8) TWOPENCE (~to pence)
13 Sneer at casual top and soft shoe (6) BOOTEE {BOO}{TEE}
18 How to make tech order confidential? (3,3,6) OFF THE RECORD {TECH+ORDER}* [RA]
22 Ebenezer, for one has no love for a Spanish bum (8) SCROUNGE {SCRO(-o+un}UNGE}
24 Trend with each custom and disappear (4,4) FADE AWAY {FAD}{EA}{WAY}
25 Scan reels (intermittently fast forwarding) lol! Entertaining from the beginning (6) RIFFLE Acrostic
26 Research from broken nails, say (8) ANALYSIS*
27 Rebel maniac touts sandwiches (3,3) ACT OUT [T]
DOWN
1 Strangely I met Lear! Live... (4-4) REAL-TIME*
2 Spooner's usual chills in shared rides? (3,5) CAR POOLS (~par cools to car pools)
3 Extravagant life! Play, act and chat... It's an illusion, literally! (8,7) PATHETIC FALLACY*
5 Solicitor's nib (4) BEAK [DD] Judge, yes. But solicitor?
6 Leo say, reprogrammed 'Cheat with Food Sizing!' (4,2,3,6) SIGN OF THE ZODIAC*
7 Request popular antioxidant perhaps (6) INVITE {IN}{VIT E}
8 Some stone dragon erected in park (6) GARDEN [T<=]
11 A pass year, extremely tame for follower (7) ACOLYTE {A}{COL}{Y}{TamE}
14 Groan! Notice about credit (card history mainly) (7) SCREECH {S{CR}EE}{Card}{Hi...y}
16 Despicable person, say, controls neighbourhood's main croaker, briefly - going up and down (2,3,3) TO AND FRO {TOA{Ne...d}D}{FROg}
17 Supporter can be heard with e-book (8) ADHERENT {HEARD*}{E}{NT}
19 Port city in Germany? Yes, couple of fellows naturally acclimatised from the beginning (6) JAFFNA {JA}{FF}{Na...y}{Ac...d}
20 Plain hard nutmeg bottles brought up (6) TUNDRA [T<=]
23 Try one whose business is picking up? (4) TAXI {TAX}{1}
Reference List
Husband = H, A in Spanish = UN, Each = EA, Year = Y, Credit = CR, Book = NT(New Testament), Yes in German = JA< Fellow = F