
The usual abundance of cluing splendour, but to be honest this puzzle is all about the amazing Homeric-onomatopoeic word for the noise of the sea at 15ac - clue of the (~8th) century (BCE), my friends. The fact that it manages to get Norwegian crime writer Jo Nesbo into the wordplay is just the icing on the cryptic cake.
Also shout-outs to the appearance of the Stones' Angie (love me a bit of pop culture in my wordplay, as you can probably tell), the awesome insult PIG-SCONCE (WOD in any other puzzle), and the eminently useful word at 26ac which I shall use to outmanoeuvre anybody who tries to wax lyrical about mere crepuscular hours at any point. All great stuff as usual, setter, many thanks for the marvellous monthly marathon!
ACROSS
Made to walk on back, I plod through prison term (10)
GRESSORIAL - reversed, all of I ROSSER "through" LAG
6 Crumpled heap in a dry bath? (4)
EPHA - (HEAP*). This is a Hebrew measure for dry goods, not to be confused with a BATH, which is quite plainly a liquid measure.
9 Edifying tales record objective I procured by dismissal being overturned (7)
EXEMPLA - reversed, all of LP ME [record | objective/accusative I] "procured by" AXE [dismissal]
10 Former tenant is like this one locking up (7)
SOCAGER - SO CAGER [like this | one locking up]
12 Porridge like heavy dough with New York pizza (5)
SADZA - SAD [like heavy/stiff dough, in baking jargon] + ZA [I'm convinced nobody in NY actually calls pizza this, but I refuse to check because it's so darned convenient for Scrabble!]
13 The most an informer recalled about copper’s weed? (9)
TARAXACUM - reversed MAX A RAT [the most | an | informer] "about" CU
14 Malice in person’s exploded into this? (5,10)
CRIME PASSIONNEL - (MALICE IN PERSON'S*), semi-&lit
15 Noisy college pub list includes Norwegian crime writer without introductions (15)
POLYPHLOESBOEAN - POLY PH LEAN [college | pub | list] "includes" {j}O {n}ESBO
20 Review of risqué artist holding fringe address to audience (9)
EPIRRHEMA - reversed RIPE [risque] + R.A. "holding" HEM [fringe]
21 It’s said to wheedle old fool (5)
COKES - homophone of COAX
23 Large single male with stylised lily for coloured skin patch (7)
EPHELIS - EP [large single, as opposed to a long player] + HE [male] + LIS [stylised lily]
24 Retreating, I conceal half of Iraq’s outstanding works (7)
RILIEVI - reversed I VEIL IR{aq}. Outstanding in a very literal sense of the word.
`
25 Peony’s back, arranged by Scottish wildflower (4)
YARR - {peon}Y ARR.
26 An intimate tea by lake at sunset (10)
ACRONYCHAL - A CRONY CHA [an | intimate | tea] by L
DOWN
1 Meshing gears rotated purplish lubricant dispenser 6,3)
GREASE CUP - (GEARS*) + reversed PUCE
2 Shoreditch’s hunks would change for the better (5)
EMEND - In Cockney aitch-dropping style, 'E-MEN'D [hunks'd]
3 Jabber during draining depression, speaking off the top of one’s head? (13)
SUPRATEMPORAL - PRATE [jabber] "during" SUMP [draining depression], + ORAL [speaking]
4 Networks, having a bit of a laugh in historic Roman province (7)
RHAETIA - RETIA [networks], having HA in
5 Donkey facilities in forest clearings (7)
ASSARTS - or ASS ARTS [donkey | facilities]
7 Old blockhead and general staff seen in photo in the old days (3-6)
PIG-SCONCE - G.S. seen in PIC ONCE
8 Mean to keep Britain completely full (5)
ABRIM - AIM [mean] to "keep" BR
11 In vain style apple core in cabbage to feed funny friend (13)
COXCOMBICALLY - COX [apple] + {cab}B{age} to "feed" COMIC ALLY
15 Malevolent person has rewritten will and distressed heirs (3-6)
ILL-WISHER - (WILL*) + (HEIRS*)
16 Song of Stones with lines about cradling special Shetland instrument (9)
LANGSPIEL - ANGIE [song of Stones], with L L "about", "cradling" S
18 Some buffaloes sicken of dusty earth (7)
LOESSIC - hidden in {buffa}LOES SIC{ken}
19 Perhaps blackberry port’s almost swallowed up overhead (7)
ETAERIO - RIO [port] has reversed EATE{n} above it
20 Sombre song for one entering Anglican cathedral site (5)
ELEGY - E.G. entering ELY
22 Rendered cheek fat that’s congealed in some places
KEECH - (CHEEK*)