Solution to 6D 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.
ACROSS
8 Spenser left salesperson confused too (4) ALSO sALSepersOn
9 Check depth of excellent bore-well in the beginning (5) PLUMB {PLUM}{Bo...l}
10 Indication from Englishman, to some extent (4) OMEN [T]
11 Landlord’s epistle (6) LETTER [DD]
12 Shatter grail after silly poem (8) MADRIGAL {GRAIL*}<=>{MAD}
13 Dress material for soldier and NCO (8) SERGEANT {SERGE}{ANT}
15 A law-man confiscates general’s plan of action (6) AGENDA {A}{GEN}{DA}
17 Haphazardly crossing without signal at first and succeeding in getting run (7) SCORING CROsSING*
19 Delivery woman? (7) MIDWIFE [CD]
22 Shout, “Start to block person who has lost his head” (6) BELLOW {Bl..k}{fELLOW}
24 Lifting device held by reportedly high queen for person who forcibly takes over vehicle (8) HIJACKER {JACK} in (~high){HI}{ER}
26 Female has torn garment scrap (8) FRAGMENT {F}{GARMENT*}
28 Lubricate rotating gear and ends of spindle (6) GREASE {GEAR*}{Sp...lE}
30 Snake gets head of tuna in vessel (4) BOAT {BOA}{T}
DOWN
1 River in Heidelberg (4) ELBE [T]
2 Get Croat gyrating for rural resident (8) COTTAGER*
3 Fight with soldiers in Greek city state (6) SPARTA {SPAR}{TA}
4 Acknowledges, “Bums sit awkwardly” (7) SUBMITS*
6 Meek medicine man on island in France (6) ?O?I?E (Addendum - DOCILE {DOC}{ILE} - See Comments)
7 Wager, accompanied by a letter (4) BETA {BET}{A}
14 Compère gets Military Cross after end of programme with ease, one hears (5) EMCEE {MC}<={p...mE} and {EE}(~ease)
16 German enemy author? (5) DEFOE {DE}{FOE}
18 Blending wine held in capital (3,5) NEW DELHI*
20 Student wearing crumpled dickey follows head of waitresses with bad intentions (8) WICKEDLY {L} in {DICKEY}* after {Wa...s}
21 Camera part that is moved to capture image of an object that is closer (7) SHUTTER [DD]
23 Illuminates answers that you are filling up in this grid (6) LIGHTS [DD]
25 Was returning after dance? It can be puzzling! (6) JIGSAW {WAS<=}<+>{JIG}
27 Leaders of rebellious individuals orchestrate turmoil and anarchy (4) RIOT Acrostic
29 Silence after South African band (4) SASH {SH}<=>{SA}
Reference List
Law-man = DA, Queen = ER, Female = F, English = EN, Soldiers = TA, Island in French = ILE, German = DE, Student = L, Silence = SH



