PREVIOUS SOLUTION

Across: 4 Obscure; 8 Immune; 9 Astound; 10 Allied; 11 Instil; 12 Rotation; 18 Patience; 20 Fringe; 21 Assist; 22 Bargain; 23 Allege; 24 Tenable.

Down: 1 Bizarre; 2 Emulate; 3 Invent; 5 Bassinet; 6 Choose; 7 Rancid; 13 Imperial; 14 Enliven; 15 Settler; 16 Grease; 17 Enigma; 19 Insult.