20 down - A red and black cap of English-designed pen from Nigeria (6) ?C???E
I'm thinking of Achebe (Chinua Achebe), but I can't unravel the cryptic part of the clue....
6 down - Insult contest involving German Booker-winner (8) – D?S?R?C?
(though not sure of the first letter being D)
10 across - Journal writer’s good and camp when out of head (4) G?D?...