No 13611, Monday 18 Jul 2022, Afterdark

Solution to 24A 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.

Never liked Chemistry!!

ACROSS

1   Severe shortage primarily, commotion about inorganic compound... (7,4) CAUSTIC SODA {CAUSTIC}{Sh...e}{ADO<=}

9   ...misuse by six with three more people at lab in the beginning... (7) VITRIOL {VI}{TRIO}{Lab}

10 ...intervene without delay, I'm not involved (7) MEDIATE imMEDIATE

11 Well, a man is smuggling an animal (5) LLAMA [T]

12 Use no bill, Harry is involved... (9) INSOLUBLE*

13 ...safeguard right away and proceed (5) ENSUE ENSUrE

15 Trouble in procuring one Indian copyright relating to the prophet (9) MESSIANIC {MESS}{I{A}N}{I}{C}

18 Fat teens with youth leader partying without a form of security (6,3) SAFETY NET {FAT+TEENS+Yo..h}* 

21 Part of door lopsided in lowest deck (5) ORLOP [T]

22 In school tour running around LA, found rubber, say (9) INSULATOR {IN+S+TOUR}* over {LA}

24 Stand's edge's large (5) E?S?L (Addendum - EASEL {EASE}{L} - See comments)

26 Earache for gladiator, rod to be removed and operated (7) OTALGIA GLAdIATOr* If ROD is removed how do we get the O?

27 Element — one free at institute for all to see by beginning of the month (7) IRIDIUM {1}{RID}{I}{U}{Mo..h}

28 A device mother broke, termed mostly faulty (11) THERMOMETER {MOTHER}*{TERMEd}*

DOWN

1   Trivial opposers to guests accommodating six (9) CAVILLERS {CA{VI}LLERS}

2   University student distributed art that is radical (5) ULTRA {U}{L}{ART*}

3   Say, phosphorous is found in ventilators, so to be removed and repaired... (9) TRIVALENT VENTILAToRs* 

4   ...CA still outside agitated ICU (7) CALCIUM {CAL{ICU*}M}

5   Mass is so-so, to be treated with diffusion, perhaps (7) OSMOSIS {M+IS+S) SO}*

6   Execute in entirety to produce an organic solvent (5) ALDOL {AL{DO}L}

7   At lab, crony creates a compound of divalent group... (8) CARBONYL* At is superfluous

8   ...at this place she's excellent (4) HERE {HER}{E}

14 Heard Kajol uses mild suds (4-4) SOFT SOAP (~cajole)

16 A few risk replacing potassium with a bit of mica for a chemical phenomenon (9) ISOMERISM {1}{SOME}{RIS(-k+m)M}

17 A compound made with two or more compounds — recreating copy, more lighter to begin with (9) COPOLYMER {COPY+MORE+Li...r}*

19 Return money — cost of salt (7) NITRATE {TIN<=}{RATE}

20 Metallic element on carved timber, posh (7) TERBIUM {TIMBER+U}*

22 Strong individual dismissed by mid-month (4) IRON {I}{RO}{moNth}

23 Weak force replaces male leader with lady (5) LIGHT (-m+l)LIGHT

25 Fast bird (5) SWIFT [DD]

Reference List

Commotion = ADO, Right = R, One = A, Indian = I, Copyright = C, Large = L, School = S, Institute = I, For all to see = U, University = U, Student = L, Mass = M, Excellent = E, Posh = U, Individual = I, Dismissed = RO(Run out), Lady = L