The Sunday Crossword No 3071, Sunday 27 Oct 2019

ACROSS
1   French pair with James Brown classic, shaking rear-ends: a theatrical device (4,2,7) DEUS EX MACHINA  {DEUs}{SEX MACHINe}{A}
8   Greedy, demanding star flipped (4) AVID<=
9   Sweet caught by hacking at tree? (7,3) CHEWING GUM {C}{HEWING}{GUM}
10 English financiers beheaded communist (6) ENGELS {E}{aNGELS}
11 Originally Byzantium, a sunlit resort? (8) ISTANBUL {By...m+A+SUNLIT}* &lit
12 Draws symbol involving face of Malcolm X (5,4) TIMES SIGN {TIES}{SIGN} over {Ma...m}
16 'By ear?' 'By ear.' 'By mouth!' (4) ORAL (~aural)
17 Siberian city? No time for Siberian city! (4) OMSK tOMSK
18 Group chant, ganglions atingle (9) SINGALONG*
23 Von Rompuy etc's sad bleatings wasting time (8) BELGIANS BLEAtINGS*
24 Clumsy poetic angler might announce this (6) OFFISH {OF}{FISH} (Addendum - OAFISH {O'FISH} - See comments)
26 Style of gown with crumpled ermine pile (6-4) EMPIRE-LINE*

27 Money invested in neuroscience (4) EURO [T]
28 Come to our gigs: dancing and a bit of philosophy (6,4,3) COGITO ERGO SUM*

DOWN
1   Morse, say, imbibing a French drink, reveals genius (2,5) DA VINCI {DCI} over {A}{VIN}

2   One from France superior to two from Italy? Inappropriate (5) UNDUE {UN}{DUE}
3   Old-time Catholic customs, offering indulgences (7) EXCUSES {EX}{C}{USES}
4   Leaderless regiment bungled encounter (7) MEETING rEGIMENT*
5   Feature with topaz, vacuous floral design (6) CHINTZ {CHIN}{TopaZ}
6   Largely popular officer (2,7) IN GENERAL {IN}{GENERAL}
7   Typical: USA messed up twice, then left (2,5) AS USUAL {USA*}{USA*}{L}
13 Relaxed with a piece of cake before departure (4-5) EASY-GOING {EASY}{GOING}
14 Ionise oddly, creating connections (3) INS IoNiSe
15 In turn, oddly missing sister (3) NUN {iN}{tUrN}
17 Candid note about amateur attempt to amuse (4-3) OPEN-MIC {OPEN}{MI}{C}
19 Encourage erection of Ulster steeple (7) INSPIRE {NI<=}{SPIRE}
20 Travel on horse, holding poem, to deliver brick (4,3) GOOD EGG {GO}{ODE}{GG}
21 Casinos: Trump taking a cut; it's bogus (7) NOSTRUM [T]
22 PM with outfit, they say, to achieve success (4,2) MAKE IT (~may kit)
25 Clears ice, reportedly (5) FREES (~freeze)

Reference List
English = E, Time = T, Old time = EX, Catholic = C, Left = L, Note = MI, About = C, Horse = GG

GRID