No 11945, Friday 03 Mar 2017, Scintillator

Scintillator seems to have got into a corner while filling the SE corner.

ACROSS
1   Impressive gold dust, with less density for good (6) AUGUST {AU}{(-d+g)GUST}
4   I have a partner that's unsound (8) IMPAIRED {I'M PAIRED}
9   Troublemaker meets end mostly near port (6) RIOTER {RIO}TERm}
10 Doctor nicely cured a round figure (8) CYLINDER {DR+NICELY}*
12 Child in multiple birth developing temperature — couple getting tense (8) OCTUPLET {T+COUPLE}* over T}
13 Every other journo in ours is inexperienced (6) JUNIOR {JoUrNo}{In}{OuRs}
15 Superstar emerging from Haiti condominium (4) ICON [T]
16 Hear and defend ill-treated liberal (4-6) FREE-HANDED*
19 Benevolent old man vanquished Satan with edged article (5,5) SANTA CLAUS {SATAN}* {CLAUSe}
20 Rip-off causing some laptops to be returned (4) SCAM <=
23 Fold leg from backside, mate (3,3) PEN PAL <= Anno not clear (Addendum - {PEN}{LAP<=} - See comments)
25 Novice recruited by CEO to stumble helplessly (8) FLOUNDER {F{L}OUNDER}
27 Overall, advanced degeneration of tiny parts of lungs (8) ALVEOLAR {OVERALL+A}*
28 Select jail, for auditors, could be a timepass (6) PICNIC (~pick nick)
29 Soldier's employer is an attentive person — nut before (8) ENLISTER (+en)ENLIST(-en)ER
30 They produced neon and acetylene (6) ETHYNE {THEY}*{NE}

DOWN
1   American priest's founding of ideology from first principles (1,6) A PRIORI {A} {PRIOR}{Id...y}
2   Two thongs cast off in deserted area (5,4) GHOST TOWN*
3   Sluggish general imprisoned by secret agent (6) SLEEPY {S{LEE}PY}
5   Mom's calling for sauce (4) MAYO {MA}{YO}
6   An advertisement that's not restricted but keen (8) ACICULAR {A}{CIrCULAR} Definition is a bit of a stretch
7   Wonderful to find two minute hands? (5) RADII {RAD}{II}
8   Colour of biblical vessel about to be covered by theologist (4,3) DARK RED {D{ARK} {RE}D}
11 Fiery republican's mistaken belief overwhelming (7) FEBRILE {R} in {BELIEF}*
14 Kicked out from big league wrestling is a German cheat (7) BEGUILE {BIG+LEagUE}*
17 Declining standard of college in New York after 70s, say (9) DECADENCY {DECADE}{N{C}Y}
18 Birds on a peepul tree harm us (8) MARABOUS {MAR}{A}{BO}{US}

19 Divided and worried after ninth month (7) SEPTATE {SEPT}{ATE}
21 Holy men's claim to fame, I'm clear, is fake (7) MIRACLE*
22 Dramatic lover putting India ahead? (6) JULIET {I before J}
24 Refreshing piece of prose (5) NOVEL [DD]
26 Ganja never attracts a calamitous woman (4) JANE [T]

GRID