SLORMGORM kicks off the week…
A smooth and enjoyable puzzle. Not sure about my parsing of 16a though.
Thanks SLORMGORM!

ACROSS
1. Hide from a kid’s big brother? (8)
GOATSKIN
GOAT’S KIN (kid’s big brother)
5. Society student left over fuss about nothing (3,3)
SOD ALL
(S (society) + L (student) + L (left)) over (ADO)< (fuss, <about)
10. One leading Rastafarian spotted in a herb store (7)
ARCHIVE
R[astafarian] (one leading) spotted in (A + CHIVE (herb))
11. Mineral finally discovered in unrefined material (7)
EARTHLY
[minera]L (finally) discovered in EARTHY (unrefined)
12. Firm with minute factory, one involved in beef (9)
COMPLAINT
CO (firm) with M (minute) + PLANT (factory), I (one) involved
13. My boss gets repelled by my interior design (5)
DECOR
(ED)< (my boss, <gets repelled) by COR (my)
15. Novelist embarrassed about a eulogy’s opening (5)
READE
(RED (embarrassed) about A) + E[ulogy] (opening)
16. Counterpart having problem with southern beastly types (8)
OPOSSUMS
OPOS (counterpart? – shouldn’t this be oppo?) having SUM (problem) with S (southern)
19. Smart bloke in nineties getting a new look (8)
EINSTEIN
(NINETIES)* (*getting a new look)
20. King must go after bit of chicanery? That’s obvious! (5)
CLEAR
LEAR (king) must go after C[hicanery] (bit of)
21. The thing to open WC in retreat could be key (5)
VITAL
IT (the thing) to open (LAV)< (WC, <in retreat)
23. Idiot cad messes about with rear of nun’s habit (9)
ADDICTION
(IDIOT CAD)* (*messes about) with [nu]N (rear of)
25. Money for investment in London? (7)
CAPITAL
27. Do away with a bishop using language priest banned (7)
ABOLISH
A + B (bishop) using [p]OLISH (language, P (priest) banned)
28. Helping people turns leader into saviour (at last!) (6)
RATION
NATION (people) turns leader into [saviou]R (at last)
29. Starting to go off by horse, don then travels around Ohio (2,3,3)
ON THE NOD
(DON THEN)* (*travels) around O (Ohio)
DOWN
1. We take short butcher’s chump of pig with cavalrymen (8)
GLANCERS
[pi]G (chump of) with LANCERS (cavalrymen)
butcher’s being rhyming slang, butcher’s hook = look
2. One who plays along with scam to panic criminal (11)
ACCOMPANIST
(SCAM TO PANIC)* (*criminal)
3. Good man with groggy head will find peace (9)
STILLNESS
ST (good man) with ILLNESS (groggy head)
4. Old people locked up in police nicks (5)
ICENI
[pol]ICE NI[cks] (locked up in)
6. A communist chasing oppressive leader with blades? (5)
OARED
(A + RED (communist)) chasing O[ppressive] (leader)
7. It’s Woody Allen’s second-favourite hotel at the front (3)
ASH
A[llen’s] S[econd-favourite] H[otel] (at the front)
8. Solicitor polishing off last of slaw and chicken? (5)
LAYER
LA[w]YER (solicitor, polishing off [sla]W (last of))
9. Try to get a better price in Britain getting lunch? That’s out of order! (4,4)
BEAT DOWN
B (Britain) + EAT (getting lunch) + DOWN (out of order)
14. I point comet out in Challenger, perhaps (11)
COMPETITION
16. They can be worn again with son expecting everyone (8)
OVERALLS
(OVER (again) with S (son)) expecting ALL (everyone)
17. Can American fool handle initially coarse material? (9)
SACKCLOTH
SACK (can, American) + CLOT (fool) + H[andle] (initially)
18. With limbs flailing, bend and arch (8)
BRANCHED
(BEND and ARCH)* (*flailing)
21. One collared by police unit briefly near Arkansas (5)
VICAR
VIC[e] (police unit, briefly) near AR (Arkansas)
22. Release Me or Relax? (3,2)
LET GO
24. Tired face of reveller seen during early morning? (5)
DRAWN
R[eveller] (face of) seen during DAWN (early morning)
26. Problem initially having sex in bed (3)
PIT
P[roblem] (initially) having IT (sex)
Thanks Slormgorm and Teacow. Misspelling “accompanist” threw me in the NW for a bit but I got over my own stupidity eventually. I am glad I am not the only only confused by “opos” instead of “oppo” – perhaps the original clue led to a solution for “opposum”.
I wasn’t sure about “O” for “Ohio” either. The official USPS history table gives it as the preferred abbreviation in 1834 but it was revised to OH by 1874 so I think an “archaic” indicator might’ve been appropriate here.
Otherwise, good Monday morning fun.
Thanks Slormgorm and Teacow
16ac: I cannot find opo with a single P either: this looks like a slip by Slormgorm – but I would be delighted to be proved wrong.
29ac: Chambers 2016 p 1061 and ODE 2010 p 1222 both have O as an abbreviation for Ohio with no indication of it being outdated. That means that the professional lexicographers working for both publishers have reason to believe that it is still in use among the general population. Official tables do not outweigh general usage.
Ohio could be O within other abbreviations, such as OSU for Ohio State University, but as a standalone abbreviation would be weird, OH being far more likely.
Lots of fun although I couldn’t do much with NE corner, thanks to Slormgorm and Teacow
Cineraria@3: I am quite ready to accept your statement that OH is far more likely, but that does not make O invalid as another possible abbreviation for Ohio.
Thanks Slormgorm and Teacow.
I’m confused by 16a. If ‘counterpart’ = OPO and ‘sum’ = PROBLEM followed by ‘southern’ = S, where does the other S come from?
That’s in addition to feeling sure that it should be OPPO.
Thanks both.
Liked Einstein, goatskin and accompanist along with many others.
3d I took groggy to be ill and head to be ness but I’m not sure it matters.
Good puzzle. I parsed 3 d the same way as James P @ 7
Liked: GOATSKIN, ABOLISH, LAYER, READE
Thanks both.
Ah, James P@7,that’s better. I did think that ‘groggy head’ for ‘illness’ was a bit weak.
Straightforward enough, apart from those pesky opossums.
Thanks, Slormgorm and Teacow.
At times, the puzzle felt like a first draft rather than the finished product, with some loose cluing and strange definitions. It was very approachable and I did enjoy it
I ticked DECOR and GOATSKIN
Thanks Slormgorm and Teacow
Thanks Slormgorm and Teacal.
Anyone else not mad about 7D? Clue works without the hyphenated “second” although clearly the surface suffers.
Apologies Teacow – sorry for autocorrect!
Agree re 16A on a friend you work with being your “oppo” as in opposite number. Could have been: “we hear counterpart…..” or similar.
But a pleasant crossie, I felt.
Piratewitch@12, the hyphen in second-favourite at 7d ASH is needed, otherwise the first letters would be ASF.
As others have mentioned, OPO seems to be a (rare) slip by Slormgorm, but since it didn’t get in the way of solving the clue, I think we can forgive him.
Thanks S&T for the fun puzzle and helpful blog.
7dn: Cellomaniac@15 is of course correct that replacing the hyphen in this clue by a space would mean that the clue did not work. But replacing the hyphenated “second-favourite” by a single unhyphenated word such as “sister’s” would make the clue more aesthetically pleasing in my opinion, and I think that is the sort of thing that Piratewatch@12 was suggesting.
While I am back in, can I say that I agree with James@7 and others regarding the parsing of 3dn.
Apologies to Piratewitch@12/13 for mistyping your username in comment 16.
“O” for Ohio was the universally recognized abbreviation for Ohio until the U.S. Post Office created official two-letter abbreviations for every state, in order to accommodate computers. Prior to that time many states had familiar three-letter designations—FLA, ARK, CAL, etc. Most of the new abbreviations are easily recognizable, but few other than residents can distinguish MA MD ME MI MN MO MS MT.
To save you looking it up:
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
Mississippi
Montana