This was effectively four puzzles in one since the quadrants were only connected by a single square in the middle of the grid.
The clues in this puzzle ranged from very easy to obscure, with one answer (6dn) and some definitions or parts of the wordplay (eg 29ac, 31ac & 18dn) that wouldn’t have been out of place in an Azed or other barred-grid puzzle. A very quick solve for me but I suspect that others may have found this one tricky in places.
All definitions are from Chambers 11th Ed.
Across
1 GROUSE GR (king {George Rex}) OUSE (river) – 2 defs.
4 REDSTART D (director) in RESTART (new beginning)
9 MAGPIE MAG (small publication) PIE (mixed print)
10 DRAUGHTS d&cd
11 BANTAM BA (graduate) NT (books) AM (before noon)
12 PATIENCE d&cd – a reference to the Gilbert and Sullivan comic opera, also known as Bunthorne’s Bride.
13 POP dd
14 RUSTLE homophone of ‘Russell’ (philosopher) – a reference to Bertrand Russell.
17 ELATION *(TOENAIL)
21 RAVAGE AV (Bible {Authorised Version}) in RAGE (anger)
25,16 CONDOR CONDO (US apartment block) R (right)
26 IN UNISON NUN (convent resident) in 11 (team) NOS (numbers) reversed
27 TOUCAN *(OUT) CAN (prison)
28 PHEASANT *(SHAPE) ANT (worker)
29 PETREL TR (Turkey {IVR}) in PEEL (Borders’ dwelling) – peel or peel-house: “orig a fortified dwelling-house, usu entered by a ladder to the first floor, with a vaulted ground floor for cattle, common on the English/Scottish Borders (historical)”.
30 ROULETTE LET (permit) in ROUTE (the way)
31 UNITES dd – unite: “an English gold coin of James I, worth 20 shillings, later 22 shillings”.
Down
1 GAME-BIRD *(AMBRIDGE)
2 ORGANIST *(ROASTING)
3 SUITABLE SUIT (outfit) ELBA (island) reversed
5 EARLAP *(AP[p]AREL)
6 SQUAIL S (small) QUAIL (1D {game-bird}) – “a counter for playing squails”; squails: “a parlour-game similar to tiddlywinks, in which small discs are snapped from the edge of the table to a centre mark”.
7 ATHENS *(HASTEN)
8 TESTER dd – “a canopy or its support, or both, esp over a bed”.
12 PONTOON dd – ‘yes and no’ indicating that ‘pontoon’ is both a card game (completely different from bridge) and a type of bridge.
15 ELL hidden in ‘towELLing’
18 NAPOLEON 3 defs. – “a French modification of the game of euchre, each player receiving five cards and playing as an individual (commonly nap)”, “a twenty-franc gold coin issued by Napoleon I” and “a small, rich iced cake with layers of puff pastry filled with cream, custard or jam”.
19 BACCARAT dd – “a French card game in which players bet money against the banker” and “a type of crystal made at Baccarat, France”.
20 REYNOLDS *(ONLY) in REDS (colours) – a reference to Sir Joshua Reynolds.
22 DIPPER dd&cd
23 BUREAU dd
24 TISSUE T (time) ISSUE (publish)
25 CORNET CO (firm) *(RENT)