Spanish river starts from remote Iberian outlands (3)

Mexican city on the Rio Grande, south of El Paso (6,6)6 Garden-fete race for riders (6,5)11 Rushes around art show, missing some of it (5)5 UN member, capital Kinshasa (3)3 Fourth Greek letter (5)5 Probationer in a religious order (6)6 Playing pieces – Odo’s and mine – all over the place! (8)8 __ Khrushchev, former leader of the Soviet Union (6)6