21a. Smear in incredible English, very badly written (10)
??R?A???L? Is the answer UNREADABLE? If so please could you explain smear and incredible English relating to the answer.
17d. Perceptive sharpness, placing university in Oxford or Cambridge (6)
Is answer ACUMEN? If so other than U for university and where do the 2 universities come in?
16d. Weapons thrown while epic is put together (8) I have answer as ASSAULTS but can't find reference to epic.