No 13783, Wednesday 08 Feb 2023, Incognito

Solution to 21D 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.

Incognito's in the US (sic).

ACROSS

1   State: "Join setter and break off" (11) CONNECTICUT {CONNECT}{I}{CUT}

9   Fruit from Walkerville, Montana (5)  LEMON [T]

10 Queen dressing cat and tailless leopard (9) CLEOPATRA {CAT+LEOPARd}*

11 Prepared tacos filled with Japanese noodle dish in US state capital (10) SACRAMENTO {SAC{RAMEN}TO*}

12 Alabama has Sulphur Monoxide, too (4) ALSO {AL}{SO}

13 Knowledgeable American expatriate initially covers conflict (5) AWARE {A}{WAR}{Ex...e}

15 Horribly vile art gallery's float in the air (8) LEVITATE {VILE*}{TATE}

17 File for fauna (8) WILDLIFE {FILE}* [RA]

19 Article on Territorial Army mentioned in Greek letter (5) THETA {THE}{TA}

22 Amount owed from young lady coming out with team leader (4) DEBT {DEB}{Team}

23 Flying erne senses the Pacific Ocean's quality of being peaceful (10) SERENENESS*

26 Big Eddy's loop (9) WHIRLPOOL [LOOP}* [RA]

27 Boy following boxer has one defence in court (5) ALIBI {B}<=>{ALI} and {1}

28 Perhaps, anaconda's expression of surprise? (5,6)  GREAT SNAKES [DD]

DOWN

1   Commanding officer on microphone is funny (5) COMIC {CO}{MIC}

2   Online rap played is matchless (9) NONPAREIL*

3   Outstrip old flame and cede wrongly (6) EXCEED {EX}{CEDE*}

4   Let rest complicated framework (7) TRESTLE*

5   Yankee followed policeman and ape (4) COPY {Y}<=>{COP}

6   Confused a little about sex appeal? Arouse! (9) TITILLATE {A+LITTLE}* over {IT}

7   Sadly, king starting to attack largest state in the US (6) ALASKA {ALAS}{K}{At...k}

8   Criminal hiding money in canoe agitated (6) CAPONE {CA{P}ONE*}

14 Forming big band (around 51) and speaking extempore (2-7) AD-LIBBING {BIG+BAND}* over {LI}

16 Silly Tehran kid is uninformed (2,3,4) IN THE DARK*

17 Having identification papers, amazes relicts (6) WIDOWS {W{ID}OWS}

18 Before noon, Goan musician is in empty fort in city in California (7) FREMONT {N}<=>{REMO} in {ForT}

20 Saint travels around university in capital of Texas (6) AUSTIN {A{U}STIN*}

21 Magician transmogrifying Mike into boy in erstwhile capital (6) ?E?L?N (Addendum - BERLIN (-m+b)BERLIN - See comments) Why erstwhile, it still is?

24 Dilapidated site contains unknown leaves (5) EXITS {E{X}ITS*}

25 Girl followed by general displays happiness (4) GLEE {G}{LEE}

Reference List

Alabama = AL, American = A, Territorial Army = TA, Young lady = DEB, Boy = B, Commanding Officer = CO, Old Flame = EX, Yankee = Y, Sex appeal = IT, King = K, Money = P(ence), Noon = N, University = U, Unknown = X, Girl = G, Mike = M