Quick –

No. 16 486

Across: 1 Inconclusive; 7 Tight; 8 Alter; 9 Leo; 10 Travelled; 11 Instal; 12 Mental; 15 Incessant; 17 Tic; 18 Llama; 19 Irate; 21 Imperfection.

Down: 1 Intelligible; 2 Nag; 3 Lethal; 4 Statement; 5 Vital; 6 Predilection; 7 Tools; 10 Translate; 13 Title; 14 Tariff; 16 Claim; 20 Arc.