7 across was a cerebral stretch …. and 19 across not in Chambers … splendid clueing
ACROSS
1 Sky cataloguer reduced 40 per cent of stars – most out of order
MESSIEST MESSIE{R} STars Charles Messier French astronomer
7 Nineteen characters back in lecture area
STOA counting back in alphabet from S to A
10 Rheumatoid arthritis drug – perhaps 8 per cent treated
ETANERCEPT ETA = 8 (PER CENT)*
11 Fighter dispatched by earlier shell
ORMER {f}ORMER
12 Poet’s opposing profits initially taken
GAINST GAINS + T
14 Source of blast: what is left seems ruined
STEAM WHISTLE (WHAT IS L SEEMS)*
15 Scottish offer to go round highland – from this attendant
GHILLIE HILL in GIE
17 Tolerated receiving butts of joking routine?
STOOGED G E in STOOD
19 Expression of gratitude which heads a Buddhist principle
TATHATA TA THAT A
22 Unmannerly but sounded bullish about bridge
LOWBRED BR in LOWED
23 Scheme initially failing afer one’s eradicated flower
PLANTAIN LILY PLAN {i}(NITIALLY)*
25 Nose is recast, revealing basis of bone
OSSEIN (NOSE IS)*
26 Publicity agent’s parade’s closing Old Street
PASEO PA’S E O
27 Thickness? Succeeded rebranding stupidities, overlooking it
SPISSITUDE (STUPID{it}IES)*
28 Fighting dogs ignoring a commotion
TOSS TOS{a}S
29 Drug, mostly pure, served in mince
HASHEESH SHEE{R} in HASH
DOWN
1 Fraternity member curtailed farmyard noises
MOOS MOOS{E}
2 Attention: the rooms will be split open by force from landslides
EARTHFALLS EAR T F in HALLS
3 Parts of feet seem damaged, I accepted
SEMEIA (SEEM)* I A
4 Less hesitant, working in secrecy
STEALTHINESS (LESS HESITANT)*
5 Tolkien creature to know wind
ENTWIST ENT WIST
6 Characteristic of Dubliner finally revealed in Joyce?
TRAITOR TRAIT O R William Joyce alias Lord Haw Haw
7 Cutting edge slices boards badly
SCISSOR BLADE (SLICES BOARD)*
8 Husband given to wine for an interval
TENTH TENT H
9 US lawyer concluded and waited to move flag
ATTENDED ATT ENDED golfing expression
13 Futile session involving English in plane
SLEEVELESS (E in LEVEL) in SESS
15 Epic events in trade treaty: one supports entry
GATEPOST EPOS in GATT
16 It’s brought in trouble in Scotland without much delay
FASTISH TIS in FASH
18 Philosophy students implying love is found in gentle touches
TAOISTS (O IS) in TATS
20 Increase in iron provided by salad plant
FRISEE RISE in FE variety of curly endive
21 Principle in book unaltered
BASIS B AS IS
24 Rising call for attention draws in grand old character
YOGH G in HOY<
< = reverse ( )* = anagram dd = double definition { } = omitted