A mid range puzzle for me with the top section, especially the NW, giving most trouble with 1ac for a long time being the wrong but possible REPOST partly because I read changes as charges. The whole thing took me close to 21 minutes but included a pink typo at the bottom. The return of the Mephisto-ish antique at 3d (different tense) was rather more fairly clued this time, so if you can remember a week back should not really cause any trouble.
No hidden clue today, but a decent set of anagrams to play with and the sound-alike clues are pretty good. I know rhotic is the often smeared sounding of a R, but don’t know if there’s a similar word for a sounded W, here ignored.
The clues are in italics, the definitions underlined, and the SOLUTIONS in bold capitals
1 Countermand second set of changes? (6)
REPEAL Hinges on the campanologist’s version of changes, a complicated sequence of bell ringing. Do it a second time, and you RE PEAL the noisy things (gloriously, of course).
4 Rush bedding that should keep camper drier (3,5)
FLY SHEET So rush converts to FLY, and bedding to SHEET. I thought it might be the same a ground sheet, but Chamber reports (in one word form) “a piece of canvas that can be fitted to the roof of a tent to give additional protection from rain”
10 Sensible planet's responsibility? (4-2-5)
DOWN-TO-EARTH In which, without the hyphens , it would be the earth’s responsibility. Gaia will be pleased.
11 Regularly removed attire? (3)
TIE Take out the even letters of aTtIrE, pretty much an &lit.
12 Boxer's reported range (7)
ROCKIES Sounds like what belongs to Rocky (Marciano or Bilboa)
14 CGS unit formerly included in dictionary (7)
OERSTED Not helped by forgetting what CGS stands for (centimetre-gram-second – that set of units) ERST used to be English for once, formerly (still is, of course, more often met in erstwhile). Stick it between the pages of the OED(ictonary)
15 Authorised airing, just what the doctor ordered? (14)
CONSTITUTIONAL Two definitions, the second “a walk for the benefit of one’s health”
17 Male radio geek's broadcast runs flawlessly (4,4,1,5)
GOES LIKE A DREAM “Broadcast” screams “anagram”. Apply to MALE RADIO GEEK’S
21 Abrasive pair of bachelors feeling sorry for nurses (7)
RUBBING Feeling sorry for, RUING, “nurses" two B(achelor)s
22 Tied up, held in college perhaps on large island (7)
LIGATED GATED is what educational establishments do to punish infractions of the rules, equivalent to being confined to barracks, currently a very common experience for a different reason in many universities (Students might mix in such a way as to pass on the Covid-19 virus – who could have guessed?). The L I comes for the standard abbreviations for Large and Island
23 Comrade's drink knocked over (3)
PAL Simple: LAP for drink reversed
24 Ineffectual vocal work almost stops popular musical returning (11)
INOPERATIVE OPER(a) for the almost vocal work bungs up IN (popular) and EVITA the musical backwards (returning) Not that that’s going to happen any time soon.
26 Smoked meat I added to previous stuff (8)
PASTRAMI Stick I on the end of PAST (previous) RAM (stuff)
27 Joined the line and collapsed (4,2)
FELL IN A double definition, the first military
1 Socialist stalwart of certain universities? (8)
REDBRICK Mine was Birmingham with the magnificent Old Joe Tower at its centre. Socialist is, of course. RED (except confusingly in America), and a stalwart is an absolute BRICK
2 What’s exclaimed when striking inmate in conflict (3)
POW Think TV series Batman with Adam West. The definition is cute
3 Outlaw historically needing to gain time (7)
ATTAINT Whodathunkit? A week ago we had the past tense of this antique word, occasioning much youwhattery and here it is again. To gain ATTAIN plus T(ime)
5 Doctor foretold extremes of Holmes' life in novel (4,2,3,5)
LORD OF THE FLIES Once memorably clued in (I think) ISIHAC as “’ullo ‘ullo, coo, coo, zip zip". Here it’s more prosaically an anagram (doctor) of FORETOLD H(olme)S (extremes) and LIFE.
6 Music beloved of the French, with variable piercing note (7)
SCHERZO Beloved of the French CHER plus variable Z in the note SO (a needle pulling thread)
7 Man of property, possibly China's James Bond? (6,5)
ESTATE AGENT I like this one: a Chinese James Bond would be an E(astern) STATE AGENT
8 The latest goal in test (6)
TRENDY Goal is END in TRY for test, as in one’s patience
9 Journalist leading session in sweeper's compact quarters (10,4)
BEDSITTING ROOM Since 1969, a fabulous absurdist film with a stellar cast, in which Ralph Richardson mutates into the title structure. Your ED journalist heads up a SITTING session, and is encapsulated in a BROOM or sweeper.
13 Priest cries out loud for ammunition (11)
CANNON BALLS I had tea with a delightful lady canon today, so was not in any way incommoded by the association, though she’s not actually a priest. Souns like (out loud) canon bawls.
16 Small fly found in child's trifle (8)
SMIDGEON Fruit fly (our local winged pest with a diurnal breeding season) didn’t fit, but the MIDGE did. Place in SON for child and you have your trifle, or maybe just a little bit of it.
18 Some people primarily colder or hotter? (7)
SPICIER The primarily apples both the Some and People, and ICIER is colder
19 Double trouble for plant (7)
DOG BANE Both words which can also mean trouble, one as a verb, the other as a noun
20 Rising whale and youngster emerge (4,2)
CROP UP Shall we have the ORC as a reversing whale and the PUP as a youngster
25 Harmful tablet, quietly disposed of (3)
ILL Just knock the musically quiet P from the tablet PILL