Harry Hoskins has the Monday puzzle in the Independent for our amusement this morning.
Abbreviations
cd cryptic definition
dd double definition
cad clue as definition
(xxxx)* anagram
anagrind = anagram indicator
[x] letter(s) removed
definitions are underlined
Across
5 Kids’ TV programme or colourful Sky show?
RAINBOW
A dd. RAINBOW was a children’s TV series that ran from 1972 to 1991.
7 Organ found in human’s thorax primarily
HEART
An insertion of EAR in H and T for the initial letters of ‘human’ and ‘thorax’. The insertion indicator is ‘found in’. A cad.
9 Liberal must get drug after I’d run out of gear
IDLE
A charade of ID, L and E for the ‘drug’.
10 Nimrod perhaps isn’t game to mess about with it
ENIGMATIST
(ISNT GAME IT)* with ‘to mess about’ as the anagrind. I dislike this kind of cliquey clue with insider knowledge of crosswords required. John Henderson is Nimrod in the Indy and Enigmatist in the Guardian, but comparatively few people solving this crossword will know that.
11 Savage getting hold of final girl by her hair?
BRUNETTE
An insertion of NET in BRUTE. The insertion indicator is ‘getting hold of’.
12 They help evacuate nurse and English old ladies
ENEMAS
A charade of EN for Enrolled Nurse, E and MAS.
14 Power grab by half-cut schmoe that plonk started off
PUTSCH
A charade of PUT and SCH[MOE].
16 When wrath will overcome quiet hope
ASPIRE
An insertion of P for the musically ‘quiet’ in AS and IRE.
18 Oscar received by writers or groups of directors
BOARDS
An insertion of O in BARDS. The insertion indicator is ‘received by’.
19 Vicar and WI upset about large domestic conflict
CIVIL WAR
An insertion of L in (VICAR WI)* The insertion indicator is ‘about’ and the anagrind is ‘upset’.
22 One in wild race with hero going round circuit ultimately?
CHARIOTEER
An insertion of both I and T for the last letter of ‘circuit’ in (RACE HERO)* The insertion indicators are ‘in’ and ‘going round’; the anagrind is ‘wild’. A cad.
24 If Nick throws first of stones then duck!
TEAL
[S]TEAL. The Obligatory Pierre Bird Link shows you the Eurasian Teal (often just referred to as the teal), a dabbling duck which is common in the UK, particularly in winter. It has given its name to the colour teal, a deep bluish-green.
25 Short kid in need of a new heart
TERSE
Hoskins is inviting you to replace the S in TEASE with R.
26 One playing on their own is totally damned, I admitted
SOLOIST
An insertion of I in SO LOST. The insertion indicator is ‘admitted’.
Down
1 Awful bother with rain for one out during colder months?
HIBERNATOR
(BOTHER RAIN)* with ‘awful’ as the anagrind.
2 Utterly wretched aim to make love close to aga
ABJECT
Another letter substitution: this time of the O in OBJECT for an A for the last letter of ‘aga’.
3 Those which get loaded in judicial assembly rooms
CHAMBERS
A dd.
4 Bridge player in Bristol affected by Brexit split
EAST
‘Split’ here is the lift-and-separate instruction, to give you BR EXIT. If BR exits from BREAST, which is what Bristol is in Cockney rhyming slang, then you end up with EAST, which is your solution.
5 One who’s up about doctor holding one up
RIDER
An insertion of I in RE and DR, all reversed. The insertion indicator is ‘holding’.
6 One in drink and one bringing the drinks?
WAITER
An insertion of I in WATER. The insertion indicator is ‘in’.
8 Group going around gallery with Will?
TESTATE
A charade of SET reversed and TATE.
13 I slept and I got up in a flap
EPIGLOTTIS
(I SLEPT I GOT)* with ‘up’ as the anagrind.
14 One predicting financial gain on the radio
PROPHET
Aural wordplay (‘on the radio’) for PROFIT.
15 Some curt criminal I patronise
CUSTOMER
(SOME CURT)* with ‘criminal’ as the anagrind.
17 Gang in the thrall of ship’s cooler guards?
SCREWS
An insertion of CREW in SS for ‘ship’. SCREW is a slang term for jail warders, or ‘cooler guards’.
20 Disgusting to hug old taxmen with IT ability?
VIRILE
An insertion of IR for Inland Revenue in VILE. The IT ability is of a sexual nature.
21 A bit isolated
APART
A charade of A and PART.
23 Bloody tricky time with leader turning to right
RARE
This is MARE (‘she was having a mare at work last week’) with the initial M replaced by R. I think.
Many thanks to Hoskins for today’s puzzle.

Couldn’t parse RARE as I have never seen that meaning for MARE. I feel that clues should be solvable to newcomers as well as solvers that don’t do the Guardian cryptics so I agree with the comment against ENIGMATIST. In its defence, the anagram fodder does heavily suggest the answer.
I should have mentioned that the derivation of MARE in that sense is an abbreviation of NIGHTMARE.
Good fun from Harry as ever although it took me some while to twig the tricky time in 23d.
I’m not entirely convinced by the definition for 11a but I guess the question mark is doing some heavy lifting. It’s a bit nit-picky, but I don’t think it’s valid to refer to Bristol in the singular in the context of 4d.
Many thanks to Hoskins and to Pierre.
Familiar with nightmare/mare so that caused no trouble but I found the shorter words tricky to crack with IDLE, TEAL and EAST the last three to fall. Tend to agree with the observation ref ENIGMATIST which is particularly tricky if there are Indy solvers who do not regularly do the Guardian. CHARIOTEER was particularly nice.
Thanks both
I second Hovis’s position (@1), ‘though “Nimrod” and “Enigma Variations” got me to the answer:(10ac);even so, it’s not a very lyrical clue, for me.
As a relative newcomer, “cliquey” in-references and devices in cryptics are a fact of life, and part of the learning curve, though sometimes a bit alienating.
MARE in 23(d) held me up, my thinking being it’s recognised slang from ” he’s having a nightmare”, ( as in having a bad game), but the “time” element didn’t click. But I can see that, “having a bad day” is commonly said to be “having a mare”.
I enjoyed the surfaces and the humour in this puzzle, some novel devices, and all fairly clued.
Big thanks, Hoskins & Pierre.
I came here for the parsing of EAST, entered without knowing why. Having now seen it, I wouldn’t necessarily agree with Rabbit Dave @3 since the original rhyming slang ‘Bristol City’ certainly refers to a singular. RARE held me up too, trying to see how ERA could ‘turn’ to the R.
Thanks to Hoskins and Pierre