No 12614, Wednesday 01 May 2019, Skulldugger

ACROSS
1   Marxist council built poor organisation (9) POLITBURO*
6   Soldier faced engineer's taunt (4) GIBE {GI}{BE}
8   Copenhagen temptress called for delicacies! (8) ?A?N?I?S (Addendum - DAINTIES (~ dane tease) - See comments)
9   Cologne wife dabbed primarily attracts Southern double-dealers (6) FRAUDS {FRAU}{Da...d}{S}
10 "She has no filter, is undiluted, on the nose", admits school principal (8,7) STRAIGHT SHOOTER {STRAIGHT} {Sc...l}}{HOOTER}
11 Positive attitude derived from American openness mostly (3-2) CAN-DO CANDOr
13 Idle outside rest room flipping bananas (8) DOOLALLY {D{LOO<=}ALLY}
15 Sugar canned in confitures, jams (8) FRUCTOSE COnFiTURES* [CA] and &lit
18 Ruling Washington in the wake of fat, arrogant Trotskyist leaders (5) FATWA {Fat}{Ar...t}{Tr...t}{WA}
20 Ramshackle zoo's gift: echidna with cancer perhaps (4,2,3,6) SIGN OF THE ZODIAC*
23 Lacking musical quality, is uptight about Tchaikovsky's oeuvre initially (6) ATONAL {A{Tc...y}{Oe...e}NAL} Anal/Uptight?
24 Captain's aide caught sailor in float without uniform (5,3) CABIN BOY {C}{AB}{IN}{BuOY}
25 It's a shame tree acreage is on the rise (4) ALAS {SAL}{A}<=
26 Portholes for rising sun viewers (5,4) BULLS EYES {BULL}{S}{EYES}

DOWN
1   President gutted about US state institute's shock feature possibly (5) PLAIT {Pr...nT} over {LA}{I}
2   Neck strap deployed if escaping from fairyland (7) LANYARD fAiRYLAND*
3   Fondness for object (5) THING [DD]
4   Suggested putting away tandoori starter, as still hungry (7) UNSATED UNStATED
5   Derivative of fantasy series originally a lot of fun (8) OFFSHOOT {OF}{Fa...y}{Se...s}{HOOT}
6   Argan oil one extracted out from breakfast fare (7) GRANOLA {ARGAN+OiL}*

7   Spooner's American agent to roar like an animal lover (9) BEDFELLOW (fed bellow to bedfellow)
12 Weapon for patrols at sea around islands (3,6) AIR PISTOL {PATROLS}* over {I} and {I}
14 Birdie scored here with this (4,4) GOLF CLUB [C&DD]
16 Sack best core boxers, for example (7) CANINES {CAN}{fINESt}
17 Principled greeting by college in overdue volte-face (7) ETHICAL {HI}{C} in {LATE<=}
19 Custodian's beginning to go crazy after evacuation from fire (7) ARDENCY {wARDEN}{CrazY}
21 God of old protects black beasts (5) ZEBUS {ZE{B}US}

22 Dated regularly on Sabbath for yonks (5) AEONS {dAtEd}{ON}{S}

Reference List
Soldier = GI, Engineer = BE, Cologne wife = FRAU, Nose = HOOTER, Rest room = LOO, Float = BUOY, Rising = BULL, Louisiana = LA, Sack = CAN, God = ZEUS

GRID