Solution to 4A 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 answer, if not solved by 1 PM.
Too may meaningless ellipses!!
ACROSS
1 Gives an address to top Nazi bodyguards going around (6) SPEAKS {S{PEAK}S}
4 Winner conceding point, essentially to get energy for powerful aim? (6) ?E?T?R (Addendum - VECTOR V(-i+e)ECTOR - See comments)
9 The article originally stirring enmity (4) HATE {THE+Ar...e}*
10 Occasion basically honouring friend someday (10) EVENTUALLY {EVENT}{h..oUr..g}{ALLY} Basically for middle letter? See comments
11 Couch empty threat in speech (without a hint of politeness, compassion, humility), starting to electioneer (6) SETTEE {SpE{Th..aT}Ech}{El...r}
12 Drew, Nancy's exposés — "Den's leaders following criminal lout at home" (8) OUTLINED {Ex...s}{Den}<=>{LOUT*}{IN} What's the role of Nancy's?
13 Amy musing about space, where mass is created (9) GYMNASIUM*
15 Constant need to be cut in half like a tree (4) PINE {PI}{NEed}
16 Beat knight, winning fight in the end (4) STIR {S{f..hT}IR}
17 Saint within right to regularly bear some sort of audience (9) LISTENERS {LI{ST}EN}{bEaR}{Sort}
21 Bond explosive ion later... (8) RELATION*
22 ... if not, alternatively, burn blue-ish sulphur (6) UNLESS {bUrN+bLuE+iSh}}{S}
24 Saw nightclub, swerved recklessly, losing direction (10) DISCOVERED {DISCO}{swERVED*}
25 Starting to fall sick, stuff... (4) FILL {Fall}{ILL}
26 ... left nose, out of oxygen finally with empty remedies, flops (6) LOSERS {L}nOSE}{Re...eS}
27 Rubs out errors in speech, insubstantial errors (6) ERASES {(~errors)ERAS}{Er..rS}
DOWN
1 People's ownership claim in secret... (7) SLAVERY {SL{AVER}Y}
2 ... electronic portal, part of programming... (5) EVENT {E}{VENT}
5 Teesta reforming land area (6) ESTATE*
6 Common practice, transferring to another country, forgetting former spouse (9) TRADITION exTRADITION
7 Dancing free, topless, live free (7) RELIEVE {fREE+LIVE}*
8 Circling radical (13) REVOLUTIONARY [DD]
14 Bores gits regularly, going into little details? (9) NUISANCES {NU{gItS}ANCES}
16 Important detail briefly disclosed, mainly about rise of AI (7) SPECIAL {SPECs}{discLosed} over {AI<=}
18 German guy's article buried by our newspaper, global agency making noise (7) THUNDER {DER}<=>{TH}{UN} What's the role of 'guy's' ?
19 Sleeps around, regularly mulls success (7) RESULTS {RES{mUlL}TS}
20 Second, place cutlery... (6) SILVER [DD]
23 ... plates, occasionally eating Indian food, primarily for feelings of happiness (5) LIFTS {pLaTeS} over {In...n}{Food}
Reference List
Nazi bodyguards = SS, Energy = E, Saint = ST, Sulphur S, Direction = SW(South West), Left = L, Electronic = E, Former spouse = EX, German guy's article = DER, Our newspaper = TH