1 down. Essential. 5 letters.
2 down. Casino spinner. 8 letters and 5 letters.
3 down. Conventional. 8 letters.
4 down. Rubber. 6 letters.
5 down. Show. 4 letters.
6 down. Hellish poem – resonant fiend (anag). 6 letters and 7 letters.
7 down. Minced and fried item. 7 letters.
12 down. Best wishes to the sneezer! 5 letters and 3 letters.
13 down. Scout’s securing device. 4 letters and 3 letters.
15 down. Little green men? 6 letters.
18 down. Vital organ. 5 letters.
19 down. Banking system. 4 letters.