Times 23,620

* = anagram
ACROSS
1 SEWER Double definition, the second a little cryptic – crossword convention allows the “false” capital in One to be used to create the surface with the misleading join coming in Channel/One.
4 SEMAPHORE Appearing for the 2nd Wed in a row! I wondered last week if younger solvers would struggle with it, but apparently not – no one commented and it’s in the Concise OED. A completely different clue this time (same)* + H in PORE
9 Louis ARMSTRONG (“Satchmo”) (1901-1971). I pencilled this in on first run through without being entirely convinced, but crossing letters confirmed and a strong arm can lift, so that’s it, I guess.
10 UP SET A set up in a tennis match.
11 RENO IR Place for quick divorces.
12 LARK SPUR Slow with this, expected the incentive to be first, but the clue is fine.
16 HAIL “Hale”
19 NOVA Bit of hesitation here, with Neva, St Petersburg’s river, also fitting, but it’s the river Avon reversed, I think, and sun is not confined the “The Sun” – it’s any big star so Nova’s OK if I’ve read it right. Flower = river, something that flows.
20 S(MATTER)ING Talk = sing = inform
26 BREV E Verb reversed. Musical note to go with those crotchets, minims, of not entirely happy memory.
27 COMPO(SI)TE Is reversed Had thought of this word as an adj but dicts confirm it’s a noun too as used here. “The composite motion” combining separate ones to make something e.g. a whole party conference can vote on.
28 LEN HU T TON One of the great cricketers (1916-1990), flourished either side of the war and made the highest ever English score in a Test (364 and that against Australia!). Surface is full of cricket imagery fast = lent five short of hundred = hu(ndred) ton = century
29 (Deb) ON AIR Deb = debutante (society girl).

DOWN
1 SEA (U)RCH IN Main = sea (was that the first crossword cliche?) We do need them and it was well concealed here.
4 SHOT Double definition.
6 P LUCKY
7 OESOPHAGI (Hoop ie = that is gas)* Plural of oesophagus, the gullet.
13 S(I)AME SE CAT (caste)*
17 (b)LIGHT Y EAR Blighty – Military slang for England (home)
24 CHINA Double definition – one of the those clues you’d have maybe to review if issuing puzzles later in book form because of the topical reference.