1 down. Not the genuine article. 5 letters.
2 down. Careless talk – doctrine is sin (anag). 13 letters.
3 down. Change channel. 4 letters and 4 letters.
4 down. (You’re) under arrest (slang). 6 letters.
5 down. Shetland or show? 4 letters.
6 down. Out of contact. 13 letters.
7 down. Floral decoration. 7 letters.
12 down. Lock up. 8 letters.
13 down. Speak theatrically. 7 letters.
15 down. Straighten (something curled up). 6 letters.
18 down. Total (without deductions). 5 letters.
19 down. Exaggerated claims. 4 letters.