A relaxing Sunday puzzle. Thanks to Silvanus. Definitions are underlined in the clues.
Across
1 Sweet smell attracts insect (6)
HUMBUG : HUM(to smell unpleasant) plus(attracts) BUG(an insect, in general).
Defn: A boiled sweet usually flavoured with peppermint.
5 Treat as insignificant piece of felt tile bent back (8)
BELITTLE : Hidden in(piece of) reversal of(… back) “felt tile bent“.
9 Clearly my usual bingo suffered following university (13)
UNAMBIGUOUSLY : Anagram of(… suffered) MY USUAL BINGO placed after(following) U(abbrev. for “university”).
10 Preserved sandwiches of last month it’s learned (8)
CULTURED : CURED(preserved, as with meat) containing(sandwiches) ULT(abbrev. for “ultimo”, of the last;previous month to the current one).
Defn: Descriptive of someone or something that is well-informed;scholarly, as in “a learned literary journal”.
11 Periodically slurp apple brandy finally in stock (6)
SUPPLY : The 1st, 3rd, 5th, 7th and 9th letters of(Periodically) “slurp apple” + the last letter of(… finally) “brandy“.
12 Boxer consumes cabbage endlessly, it neutralises acid (6)
ALKALI : ALI(Mohamed, the champion boxer) containing(consumes) “kale”(a hardy cabbage) minus its last letter(endlessly).
14 Verbally treat with contempt stage productions and shows (8)
DISPLAYS : DIS(to speak of;verbally treat with disrespect;contempt) + PLAYS(stage;theatrical productions).
16 Tree-dwelling snake’s about, tip off Spanish royal (8)
ARBOREAL : Reversal of(…’s about) “cobra”(a highly poisonous snake) minus its 1st letter(tip off) + REAL(Spanish for “royal”).
19 It encourages rapid development in established case pursuing stolen barrels (6)
HOTBED : The 1st and last letters of(… case) “established” placed after(pursuing) [HOT(descriptive of stolen property) + B(abbrev. for “barrels”) ].
21 Insult of little significance (6)
SLIGHT : Double defn.
23 Possibly fluke throw that disfigures the grass (8)
WORMCAST : WORM(an example of which;possibly, is the fluke, a parasitic flatworm) + CAST(to throw).

25 Top rival chose to work in Westminster perhaps (7,6)
PRIVATE SCHOOL : Anagram of(…. to work) TOP RIVAL CHOSE.
Defn: An example of which;perhaps, is Westminster School in London, an independent private school, also called a public school, which inspite of its name is not public-funded.
26 Soldiers needing time amongst some moving souvenirs (8)
MEMENTOS : [ MEN(soldiers) plus(needing) T(abbrev. for “time”) ] contained in(amongst) anagram of(… moving) SOME.
27 Fondness of musical, on no longer (6)
LIKING : “Lion King”(the stage musical) minus(… no longer) “on”.
Down
2 It’s rare, although Tom Jones begs to differ? (7)
UNUSUAL : Cryptic defn: Refering to Tom Jones’s hit song “It’s Not Unusual”, a title in contradiction to “It’s Rare”.
3 Expression of annoyance from bishop when in late regularly (5)
BLAST : B(abbrev. for “bishop”, in chess notation) + [ AS(when, as in “as you pass him, look right”) contained in(in) the 1st and 3rd letters of(… regularly) “late” ].
4 German poet wearing excellent new English coat (9)
GABARDINE : G(abbrev. for “German”) + [ BARD(a poet) contained in(wearing) AI(A1;first class quality;excellent with “1” substituted by its Roman numeral) ] + N(abbrev. for “new”) + E(abbrev. for “English”).

5 Swinging handbag, daughter knocks out penultimate member of gang in foreign capital (7)
BAGHDAD : Anagram of(Swinging) [ “handbag” with “d”(abbrev. for “daughter”) replacing(knocks out) the last but one letter of(penultimate member of) “gang” ].
6 Aircraft manoeuvres in wind, climbing … (5)
LOOPS : Reversal of(…, climbing, in a down clue) “spool”(to wind;coil on to, well, a spool).
7 … doubly a trial for one on maiden flight? (4,5)
TEST PILOT : TEST(a trial) plus(doubly) PILOT(a trial;something done on a smaller scale before being introduced more widely).
8 Republican shunned by monarchy left instead to committed following (7)
LOYALTY : “R”(abbrev. for “Republican”) deleted from(shunned by) “royalty”(monarchy) replaced by(… instead) “l”(abbrev. for “left”).
13 Adjacent whisper admitting thirst (9)
ALONGSIDE : ASIDE(a whisper, not intended to be heard by everyone present) containing(admitting) LONG(to thirst;yearn for).
15 Round his place oddly beginning to rage inside (9)
SPHERICAL : Anagram of(… oddly) HIS PLACE containing(… inside) the 1st letter of(beginning to) “rage“.
17 Raising fruit tree against wall, I overlooked return of disease (7)
RELAPSE : Reversal of(Raising, in a down clue) “espalier”(a fruit tree whose branches are trained to grow flat against a wall) minus(… overlooked) “I“.

18 Act inferior and unruly (7)
LAWLESS : LAW(an act passed in Parliament) + LESS(inferior;of lower rank or importance).
20 Greek character crosses line with ill-treatment of ponies (7)
EPSILON : L(abbrev. for “line”) contained in(crosses … with) anagram of(ill-treatment of) PONIES.
22 Brown starts to take over after Blair’s stint ends (5)
TOAST : The 1st letters, respectively, of(starts to) “take over after” + the last letters, respectively, of(… ends) “Blair’s stint“.
24 Thief‘s unpleasant to an Australian (5)
CROOK : Double defn: 2nd: …, in the local slang.
Fairly straightforward, with a few clues needing extra concentration and a couple parsed post-solve.
Loved the surfaces of 27 and 22.
Thanks scchua and Silvanus.
Yes, mostly went in pretty easily though with a few such as WORMCAST which needed a bit of thought. Missed the parsing of LIKING despite I think having seen the clue, or a very similar one, somewhere else. Should have known, but didn’t, B as an abbreviation for “barrels”, and can’t remember having seen it used as such in cryptic land before.
The surface for TOAST was good as swatty@1 says, and where the ‘starts’ ended and the ‘ends’ started took some working out.
Not a very exciting clue but CROOK was my favourite. ‘Things are crook in Tootgarook’ is a saying I use (too) often.
Thanks to Silvanus and scchua
Yes, pretty straightforward for the most part with a few head-scratchers thrown in. I felt that 14a was meant to be taken as DISS for ‘treat with contempt’ with ‘verbally’ to denote the missing S. However, since DISS can be spelt with one S, the initial word isn’t really necessary. I don’t think DIS necessarily refers to a verbal treatment of contempt. Thanks to all.
I was slower at this than I probably should have been. My favourites are the pair of LOOPS and TEST PILOT. Thanks Silvanus and scchua.
I thought this was great fun and also learned something new in the Australian expression.
Tom Jones amused despite the fact that I’ve never been a fan and I liked the brevity of 21a. Plenty of clever clues worthy of mention but my top spot went to 1a.
Thanks to Silvanus (wish we saw more of your output on here) and to scchua for the blog.
Thanks Silvanus. Always nice to see one of your puzzles. Foi was unambiguously, Loi was liking, after a minor struggle with se. Then it took me another few minutes to remember the musical so the parsing made sense. Agree with swatty about the good surfaces of 27and 22.
The private vs public school thing has always confused me.
Many thanks scchua as always
All pretty straightforward. The second meaning of CROOK was new to us but the answer was obvious from crossing letters, and we couldn’t parse HOTBED, which again was an obvious answer.
We did wonder if there was going to be a theme when the first three across rows (ignoring the unches) contained multiple U’s but guess that was just fortuitous.
No CoD – it was all good.
Thanks, scchua and Silvanus.
Setter here, many thanks to scchua for his decryptions and to everyone else who took the trouble to leave comments. They are always greatly appreciated.
Good crossword, easyish but not too easy.
As someone who is, probably unlike the average solver, very much interested in ‘technical’ issues, I wasn’t fully comfortable with 22d (TOAST). Yes, a splendid and ‘meaningful’ surface but the apostrophe S at the end raised doubts whether it’s OK to have S as the first of the two ‘ends’.
Many thanks to today’s setter and scchua.
Sil @9. I have to admit having the same unease with 22d but let it pass due to the surface.
I am pretty sure that I could come up with a more clever, less lazy clue for 3 down in my sleep. How about “Born –
finally a good time”.