1 down. Sock – to a grasshopper? 4-4 letters.
2 down. Possibly (this month)? 5 letters.
4 down. Birds trained to return. 6 letters and 7 letters.
5 down. Greasy, wooden or runcible. 5 letters.
6 down. Provocateur. 7 letters.
7 down. Eg wych or Dutch. 4 letters.
8 down. Receives blows. 6 letters.
13 down. Tile-maker? 8 letters.
15 down. Without assistance. 7 letters.
16 down. Truth. 6 letters.
18 down. A town (anag) – another name for Odin. 5 letters.
20 down. Allow (dough) to rise. 5 letters.
21 down. ___ number (used in measuring high speeds). 4 letters.