Solution to 30A 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
7 See 25
8 Lao museum built building in memory of departed person (9) MAUSOLEUM*
11 Hint: Medicinal alcoholic solution used by doctors long back (8) TINCTURE [DD]
12 Force mother to appear before English trade union before beginning of May (8) MOMENTUM {MOM}{EN}{TU}{May}
14/27 Aerial performers zip cruising wildly around top of church (6,6) FLYING CIRCUS {FLY} and {CRUISING}* over {Ch...h}
16 Cheat the French to let a little flow (7) TRICKLE {TRICK}{LE}
18 Arrange ten logs having maximum length (7) LONGEST*
25/7 Buoyant components of the skeleton? (8,4) FLOATING RIBS {FLOATING}{RIBS}
29 Damaged top hat too may be something likely to be dropped (3,6) HOT POTATO*
30 Killed a large number (4) S?E? (Addendum - SLEW [DD] - See comments)
DOWN
1 Rob a creature (4,4) WILD BOAR {ROB+A}* [RA]
4/23 Government servants following traditions looking forward to their bit of duty? (7,8) CUSTOMS OFFICERS {OFFICERS}<=>{CUSTOMS} Semi&lit
5 Fat donor dancing back and forth (2,3,3) TO AND FRO*
6 Latest model salamander (4) NEWT {NEW}{T}
13 Heard Bond’s boss goes ahead of the real chief of MI6 to become Master of Ceremonies (5) EMCEE (~ em{M} before cee{C})
15 At last, lady who sang Hindi lyric is referring to an Indian system for good health (5) YOGIC {ladY}{whO}{sanG}{h..dI}{l..iC} Tail Acrostic
17 See, pill is returned before operation to obtain sweet (8) LOLLIPOP {LO}{PILL<=}{OP}
19 Her odd US design’s hidden (8) SHROUDED*
20 Minimal activity when gal wore make-up (3,4) LOW GEAR*
22 Mix bleach without a burp (5) BELCH BLEaCH*
24 Agent to take into account (6) FACTOR [DD]
26 Does recast cast (4) ACTS*
28 Trustee conceals result of oxidation of metal (4) RUST [T]
Reference List
English = EN, Zip = FLY, The in French = LE, Left = L, Model = T, Bond's boss = M, Chef of MI6 = C