SOLUTION TO PUZZLE NO. 16,666

Across: 1 One-day strike; 7 Cubit; 8 Photo; 9 Rio; 10 Gift token; 11 Clever; 12 Abrade; 15 Mismanage; 17 Goa; 18 Night; 19 Stems; 21 Hydrostatics.

Down: 1 One track mind; 2 Alb; 3 Set off; 4 Reputable; 5 Kiosk; 6 Countenances; 7 Crone; 10 Goes after; 13 Aegis; 14 Lasses; 16 Soggy; 20 Era.