Thank you to Gurney. Definitions are underlined in the clues.
Across
1. Drink distributed in eastern US (9)
SAUTERNES : Anagram of(distributed in) EASTERN US.
Defn: A French sweet wine from the region of the same name.
6. Officer at sea bawling out sailor upsets newcomers at start (5)
BOSUN : 1st letters, respectively, of(… at start) “bawling out sailor upsets newcomers“.
9. Club has outside somewhere to swim (5)
BATHS : BAT(a club) + 1st and last letters of(… outside) “has“.
10. One unfairly blamed is rested, inspiring better English attempt (9)
SCAPEGOAT : SAT(rested on a seat) containing(inspiring) [ CAP(to better/to outdo) + E(abbrev. for “English”) + GO(an attempt/a try at something) ].
11. Aren’t at all trained for dance (10)
TARANTELLA : Anagram of(… trained) AREN’T AT ALL.
: emergency therapy after being bitten by this?: 
12. Successor of Ambassador, Irish (4)
HEIR : HE(abbrev. for “His Excellency”, a form of address for an ambassador) + IR(abbrev. for “Irish”).
14. Partner kind with prisoner (7)
CONSORT : SORT(kind/type) placed after(with) CON(short for “convict”, a prisoner).
15. First loch to feature in article – it’s emblematic (7)
THISTLE : [ IST(1st/first, with the Roman numeral substitution) + L(abbrev. for “loch”) ] contained in(to feature in) THE(article in English grammar).
Defn: …, as used by the Scottish.
17. Finished first helpings of everything at table? Pig! (7)
OVEREAT : OVER(finshed/completed) + 1st letters, respectively, of(first helpings of) “everything at table“.
Defn: To … like, well, a pig.
19. Eerie with first appearance of antipathy for love? Horrible! (7)
GHASTLY : “ghostly”(eerie/unreal) + 1st letter of(first appearance of) “antipathy” replacing(with … for) “o”(letter representing 0/love in tennis scores).
20. Disadvantage of small horse (4)
SNAG : S(abbrev. for “small”) + NAG(an old or unhealthy horse).
22. After graduate comes to essential point, assess court official (10)
MAGISTRATE : MA(abbrev. for “Master of Arts”, a graduate) plus(comes to) GIST(the essential point of a speech or text) + plus(After …) RATE(to assess/to judge the value of).
25. Avoiding pub maybe, not present to receive money (9)
ABSTINENT : ABSENT(not present/being somewhere else) containing(to receive) TIN(slang for “money”).
Defn: …, and hence abstaining from alcohol (or crisps or pub food).
26. At audition rocked in leather (5)
SUEDE : Homophone of(At audition) “swayed”(rocked to and fro).
27. Review of rent day to be widely discussed online (5)
TREND : Anagram of(Review of) RENT + D(abbrev. for “day”).
Defn: …, as the subject of many posts on social media.
28. Tough owner’s horses, not half-decent (9)
STRINGENT : STRING(collective noun for horses owned by an individual person or entity) + “decent” minus its first 3 letters(not half…).
Defn: …/strict.
Down
1. A little way along, discards a bothersome item of footwear (5)
SABOT : Hidden in(A little way along) “discards a bothersome“.
2. Unqualified – a new Church statement (9)
UTTERANCE : UTTER(unqualified/absolute) + A + N(abbrev. for “new”) + CE(abbrev. for the Church of England).
3. President is in from France – what’s brought about that? Force ignored at start (10)
EISENHOWER : [IS + EN(from France/French for “in”) ] contained in(…’s brought about that) EH?(a sound to express inquiry/”what?”) + “power”(force, loosely speaking/might) minus its 1st letter(ignored at start).
Defn: Former … of the US.
4. Beginning northern climb (7)
NASCENT : N(abbrev. for “northern”) + ASCENT(a climb).
5. One with potential beginning to entertain the French (7)
STARLET : START(the beginning) containing(to entertain) LE(French for the article “the”).
Defn: A young actress with potential to become a star.
6. Mixture of, oddly, barley and whiskey (4)
BREW : 1st, 3rd and 5th letters of(oddly) “barley” plus(and) W(letter represented by “whiskey”, in the phonetic alphabet).
7. It might be buttered in historic Scottish place (5)
SCONE : Double defn.
… or clotted-creamed and jammed; and 2: the Palace: 
8. Yet to iron slips, getting reputation? (9)
NOTORIETY : Anagram of(… slips) YET TO IRON.
Defn: … for some bad quality or bad deed.
13. New bar pianist widely supported (10)
BIPARTISAN : Anagram of(New) bar pianist.
14. Pass over worker scoffing one breakfast item? (9)
CROISSANT : CROSS(to pass over/go over to the other side, as with a road, say) + ANT(a social insect, one that belongs to the worker caste) containing(scoffing) I(Roman numeral for “one”).
16. Four identical notes about a private conversation? (4-1-4)
TETE-A-TETE : TE,TE,TE,TE(4 of the same note on the musical sol-fa scale) containing(about) A.
18. They might poke fun at posers? (7)
TEASERS : Double defn: 2nd: … that will tease your brain.
19. Brilliance of ultimately charming new arrivals? (7)
GLITTER : Last letter of(ultimately) “charming” + LITTER(new born babies/arrivals at one time of an animal).
21. Place to walk one’s going to by the sound of it (5)
AISLE : Homophone of(… by the sound of it) “I’ll”(I will/one is going to/intending to).
23. Contest on equal footing over time (5)
EVENT : EVEN(on equal footing/equally balanced) placed above(over, in a down clue) T(abbrev. for “time”).
24. Meander, getting trade maybe (4)
WIND : Double defn: 2nd: …, a trade wind that is.
Pleasant and not too difficult, though I found my last in STRINGENT quite, well, ‘Tough’ as I didn’t know STRING for ‘owner’s horses’. The parsing of others such as UTTERANCE and EISENHOWER also took a bit of working out.
Favourites were BOSUN (‘Officer’ will do, but more specifically a petty officer) and THISTLE.
Thanks to scchua (nice pic of our cute and cuddly arachnoid friend) and Gurney
I’m another who didn’t know ‘string’ of horses though the answer was clear. Also needed this blog to see the parsing of SCAPEGOAT but otherwise, an enjoyable saunter through this grid.
I nominate TETE-A-TETE and NOTORIETY as favourites today.
Thanks to Gurney and Scchua for the meticulous blog and striking visuals as always.
Thanks to Scchua for the admirable illustrated blog. Nothing to add on the puzzle – pleasant if undemanding.
Thanks for the blog and the pictures. A lot of nice, neat clues here. I really liked STRINGENT and GHASTLY was very clever.
L as an abbreviation for loch. Really?
Thanks Gurney and Scchua
New@5 : L for loch is in Chambers 2014 (p. 853) and doubtless in other dictionaries.
A pleasant and fairly quick solve with no real problems. The parsing of EISENHOWER took a bit of working out and we thought initially that the graduate in 22ac might be a BA and the essential point the middle I of ‘point’ leading to something like a bailiff but soon found that was a blind alley.
BOSUN, NOTORIETY and CROISSANT were among our favourites.
Thanks, Gurney and scchua.
L = loch is probably on maps too.
Many thanks for the excellent blog, scchua, and for all the illustrations. Many thanks also to all those who commented. L = loch was used in the clue as the answer was THISTLE referring to the Scottish emblem. The abbreviation is is in Concise Oxford, alongside that for lough and lake, referring, as mentioned above, to its use on maps.
Thanks Gurney and scchua
A puzzle done in short bursts throughout the day – often wonder if the experience would be different if one gets the chance to have a solid single sitting to do it.
Loved some of the surfaces here – particularly BOSUN and CROISSANT. Was challenging word play, as stated above, for EISENHOWER and had to wait for the penny to drop with the ‘trade’ at 24d.
Finished with that WIND, the clever GHASTLY and GLITTER the last one in.
Late to the party but count me as a fan of this crossword with GHASTLY, UTTERANCE, and STARLET among my favourites. Thanks to both.