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11a A rich sauce made from egg yolks, lemon juice or wine vinegar, butter, shallots, herbs and seasoning (9)
12a A backless sofa or couch, designed to be set against a wall (5)
13a Widely cultivated tree bearing sweet, gritty-textured, juicy fruit that has a globular base and tapers towards the top (4)
15a One of the Ionian islands; regarded as the home of Homer's Odysseus (6)
17a A small marine food fish of the Herring family (7)
19a An officer who commanded a Roman unit of foot soldiers (9)
21a Secret agreement for a fraudulent purpose; connivance; conspiracy (9)
22a ******* the First, the first Russian Tsar of the House of Romanov (7)
23a Type of bird known for laying its eggs in the nests of other birds (6)
26a Alloy containing iron, nickel and carbon with a very low coefficient of expansion (5)
1d A rubber substance derived frm the coagulated milky latex of a type of tropical tree that is used in dentistry (5-6)
2d Another name for a killer whale (4)
4d A rapid keyboard composition dating from the baroque peroid, usually in a rhythmically free style (7)
5d Narrow, shelf-like beds fixed along a wall (5)
8d A wantonly vicious or cruel act (7)
14d A wickerwork trap for catching lobsters, etc. (5)
Relating to, sung by or designed for an organised group of singers (6)
17d A logic-based, number-placement puzzle (6)
20d A method for detecting the position and velocity of a distant object, such as an aircraft (5)
22d Gian Carlo *******, Italian American composer whose works included the opera 'Amahl and the Night Visitors' in 1951 (7)
23d A drain or covered channel that crosses under a road, railway, etc. (7)
24d To start play in a game of football (4,3)
29d A tropical African tree whose oily seeds yield a butter-like, white fat used in food, soap-making, etc. (4)
30d A long, shallow basket made of curved strips of wood, used for carrying flowers, fruit, etc. (4)