No 13624, Tuesday 02 Aug 2022, Arden

Solution to 21A 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.

ACROSS

1   Insult another ruler (6) SULTAN [T]

4   Traitor will regularly lampoon, say... (8) APOSTATE {lAmPoOn}{STATE}

9   ...fools take time, is it worth? (6) ASSETS {ASSE{T}S}

10 Expressing doubt about spade work in capital (8) BUDAPEST {BU{SPADE*}T}

12 Dimensions of money, this has no interest (8)  BREADTHS {BREAD}{THiS}

13 Want to be a father? Keep quiet (6) ASPIRE {A}{S{P}IRE}

15 Hiring again with harvest giving some indications (12) REAPPOINTING {REAP}{POINTING}

18 Herb's off — boards plane on time finally (8-4) LEOPARDS BANE {BOARDS+PLANE}*{timE}

21 Self-starter with a place to live, extremely sensible (6) S?N?S? (Addendum - SANEST {Self}{A}{NEST} - See comments)

22 Instrument to play latest music — learn it, perhaps (8) CLARINET {m..iC}{LEARN+IT}*

24 Islanders establish overall ancestry (8) BALINESE {BA{LINE}SE}

25 Washer and empty cartridge in box (6) SPACER {SPA{Ca...gE}R}

26 Art is very famous (4,4) ROCK STAR {ART}* [RA]

27 Already fast, city wise they're in the centre (2,2,2) AS IT IS {fASt}{cITy}{wISe}

DOWN

1   Band on the road carrying empty bag or a sheath (8) SCABBARD {ABBA}{RD}<=>{SaC}

2   What a gambler possibly salvages here (3,5) LAS VEGAS* Semi&lit

3   Like to have working president, sent these to fight depression (15) ANTIDEPRESSENTS {AS} over {PRESIDENT+SENT}*

5   Choice to pare the fat somewhat (4) PLUM PLUMp

6   Use spartan dress, it's standard (5,3,7) STARS AND STRIPES*

7   American flying ace, a mile away (6) AMELIA {A}{A+MILE}*

8   Vietnamese have become vain with pride (6) ESTEEM viETnaMESE*

11 The fleet drops one, crosses the border for some prawns (7) SHRIMPS {SH{RIM}iPS}

14 Old houses, right time to frighten (7) STARTLE {STA{R}{T}LE}

16 Hold on, allow business partners to come up and fix the wooden panelling (8) WAINSCOT {WAIT} over {CO}<=>{NS}

17 Studies cover true representation, some old people use them (8) DENTURES {DEN{TRUE*}S}

19 Regular mission except for a line on the weather map (6) ISOBAR {mIsSiOn}{BAR}

20 To make carbon steel, change rates altogether (2,4) EN BLOC {CarBON+steEL}*

23 From the South part of Australia is adjoining this land mass (4) ASIA [T<=]

Reference List

Time = T, Money = BREAD, Interest = I, Quiet = P, Road = RD, Ace = A, Right = R, Partners = NS(North, South in Bridge game)