The puzzle is available here.
Hi everyone. This was a bottom up solve for me which felt difficult but actually took less time than usual for a Monk. I did have some help from the nina though. There are some related thematic entries which I didn’t notice at the time. I have highlighted the obvious ones below, but there is a little more associated content to be found, such as in the clue for 8d.
When blogging I noticed a few instances of one or 1 being represented by the letter I, notably in the first three across clues. Nevertheless, an ace puzzle – thanks Monk!
Definitions are underlined in the clues below. In the explanations, quoted indicators are in italics, explicit [deletions] are in square brackets, and I’ve capitalised and emboldened letters which appear in the ANSWER. For clarity, I omit most link words and some juxtaposition indicators.
Across
9a Old coastal area is excellent, best seen from the east (5)
IONIA
AI (A1: excellent) and NO I (No 1: best) all reversed (seen from the east, in an across entry)
10a American leave, one taken in an Eastern French region (9)
AQUITAINE
A (American) + QUIT (leave) + I (one) inside (taken in) AN and E (Eastern)
11a One left outside quietly stopping search, turning back dogs (7)
KELPIES
The reversal of (… turning back) I (one) and L (left) surrounding (outside) P (quietly), all inside (stopping) SEEK (search)
12a Retreat from ledge and end, pulling back from both (7)
SHELTER
SHELf (ledge) and TERm (end), removing the final letter from each (pulling back from both)
13a Famous brand set in stone (9)
EXCALIBUR
A cryptic definition, the brand being a sword
15a Wherein some early Latin recalled? (5)
ITALY
The answer to the question posed by the clue is found in some earlY LATIn reversed (recalled)
17a This will get you free dinners — optimism worked (15)
DISIMPRISONMENT
An anagram of (… worked) DINNERS OPTIMISM
20a Tree in estate, say, outside England’s borders (5)
CEDAR
CAR (estate say) around (outside) EnglanD’s outer letters (borders)
21a Gloomy yet funny linguistic study (9)
ETYMOLOGY
GLOOMY YET anagrammed (funny)
23a Judges expelling just who fixed skating event (3,4)
ICE SHOW
[just]ICES (judges) removing (expelling) JUST + an anagram of (… fixed) WHO
25a Long, drawn vote securing Independent win (7)
ACHIEVE
ACHE (long) and VotE without its inner letters (drawn …, as in eviscerated) around (securing) I (Independent)
26a On which Spartans perhaps grow replete, possibly after adult pressure (5-4)
APPLE-TREE
An anagram of (… possibly) REPLETE after A (adult) and P (pressure). Spartans are a variety of apple
27a Agreement about hosting overseas ruler (5)
EMEER
AgREEMEnt in reverse (about) is holding (hosting) the answer
Down
1d Extract marijuana plant (8)
MILKWEED
MILK (extract) + WEED (marijuana)
2d Made English chemical company second, having fished around (10)
ANGLICISED
ICI (chemical company) and S (second) surrounded by (having … around) ANGLED (fished)
3d Artist set out, climbing out of the centre (6)
RADIAL
RA (artist) + the reversal of (… climbing, in a down entry) LAID (set out)
4d Disease of solvers picked up (4)
YAWS
YOURS (solvers), homophone (picked up)
5d Composer‘s rising rank, er, undermined by British media conglomerate (10)
MUSSORGSKY
In reverse, (rising) GROSS (rank) and UM (er), all followed by (undermined by) SKY (British media conglomerate)
6d Immediately overwhelmed by alpha male, one in particular from a European capital (8)
ATHENIAN
THEN (immediately) surrounded by (overwhelmed by) A (alpha) and IAN (male, one in particular)
7d Top of rock having twelve-inch fissure (4)
RIFT
The first letter (top) of Rock + I FT (1 ft: twelve-inch)
8d Variable, premature annual (6)
YEARLY
Y (variable) + EARLY (premature)
14d Plant holder raised on mortar, centrally below block (10)
BARRENWORT
OWNER (holder) reversed (raised) preceding (on) the middle letters of (… centrally) moRTar, all below BAR (block)
16d New name given to shooting star moving over weather instrument (10)
ANEMOMETER
An anagram of (new) NAME + METEOR (shooting star), moving O (over)
18d Tramp and Monk joining new border dwellers (8)
MARCHMEN
MARCH (tramp) and ME (Monk) + N (new)
19d Plant transplants by artery (8)
TAYBERRY
The answer is an anagram of (transplants) BY ARTERY
20d French president‘s right answer given in style (6)
CHIRAC
R (right) and A (answer) are inside (given in) CHIC (style)
22d Plant sheath having yellowish-brown area (6)
OCHREA
OCHRE (yellowish-brown) + A (area)
24d Show bombshell with casing removed (4)
EXPO
sEXPOt (bombshell) without outer letters (with casing removed)
25d Maple syrup essentially put beneath one (4)
ACER
The middle letter of (essentially) syRup put beneath ACE (one)

Don’t forget to highlight the other word from the Nina.
It is done!
Oh no it isn’t
It’s in the central column!
That was fun. Thanks both.
With all the plants, I was sure 18d was going to be MARSH… But no
Thank you all, especially the appropriately-named Herb. Clearly time for something caffeinated, I think …
Needed help from Miss Kitty with the 4d disease and the 14d plant. Could perhaps have figured out the former had I registered the Nina in time but I never thought of the ‘holder’ in 14d.
Particular favourites were MILKWEED & CHIRAC.
Thanks to Monk and to Kitty for her assistance – enjoy your caffeine, I could perhaps have done with an extra cup!
Failed to spot the Nina, couldn’t parse BARRENWORT (plus nho), IONIA held out for ages even though obvious once seen and I thoroughly enjoyed it all.
Thanks to Monk, Kitty and other posters for final piece of Nina.
Thanks both. An enjoyable struggle, if there can be such a thing. I’m still tasking my brain on how ‘then’ in ATHENIAN can mean immediately, as it means so many things which contradict that definition, but I am sure it is fair, if potentially obscure, as everything else was
DNF but wholly enjoyable, despite a small gripe: Excalibur was set in an anvil not in stone. According to Merlin, that is….
Must admit finding monk puzzles intimidating but guess fairly early the Mary Mary bit which really helped. Thanks monk and the kitty.
Really fun to be able to work out unknown words from wordplay! I don’t know how I missed the Nina…
Thanks Kitty and Monk.
Excellent.
Saw ‘contrary’ first and used up C, N, and T; not knowing the rhyme, after getting the second Mary, Googled to get the first; very helpful for NW.
Failed to see QUITE, though….well.
ICE SHOW top fav.
Seeing QUITE helped me get AQUITAINE
Super puzzle. Liked the mention of Tramp-nice to see his name on the G Prize
Good stuff. Thanks all,
Here’s a pic of what I think of as KELPIES.
I’ve only recently started doing Independent crosswords, not quite on the same wavelength yet, but getting there.
Thanks Monk & Kitty (good illustrations)