Solution to 1D 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.
Open for anyone to solve, if not solved by 1 PM.
ACROSS
6 Exult as the ultimate champion bags final medal (5) GLOAT {G{m..aL}OAT}
7 Fancy yachts carrying it is seen as a virtue (8) CHASTITY {CHAST{IT}Y*}
11 Activity protects America flooding (7) DOUSING {DO{US}ING}
12 Fought over how the woman was dressed overall (7) CLASHED {CLA{SHE}D}
19 Home gets, say, butane fuel (7) BAGASSE {BA{GAS}SE}
23 Help set back foundation of black granite (7) DIABASE {AID<=}{BASE}
26 Copier, it provided a welcome drink (8) APERITIF {APER}{IT}{IF}
27 Works with team leader on lubricants (5) TOILS {Team}{OILS}
DOWN
1 Combine ideas with Charlie, one gets even (8) ?O?F?A?E ()
2 Request architects to provide a stiffener (6) STARCH [T]
3 Agreement that electric cable can be wound close to armature (10) ACCORDANCE {AC}{CORD}{CAN*}{a...rE}
4 Poet's come up with something mediocre (4) BARD<=
5 A material to suit oneself (2,4) AT WILL {A}{TWILL}
6 Malfunction starts - good luck charm has it inside (6) GLITCH {Good}{Luck}{CH} over {IT}
8 Huge waves have no rocky mountains (7) TSUNAMI {TSUNAMI+NO}*=MOUNTAINS [CA]
13 Angry VIP will raise (7,3) CHEESED OFF {CHEESE}{DOFF}
15 Anguish of the French couple (7) DESPAIR {DES}{PAIR}
16 Denied profits, Matilda dropped the odds (8) GAINSAID {GAINS}{mAtIlDa}
17 Follow a union member right away (5) ABIDE {A}{BrIDE}
18 Greek gods deal with strays (6) SATYRS*
20 Drink and academic performance gets hit (6) GRAPPA {G{RAP}PA}
24 Leaders enjoy and take sufficient provisions (4) EATS Acrostic
Reference List
Ultimate champion = GOAT(Greatest of all time), Electric = AC, Charm = CH, Of in French = DES, Right = R