Stuck on these clues,any help appreciated,thank you.
19 across- One time clue cryptically "before noon" as " before daybreak"(9)
A??E????N
18 across- A cyclist's hazard however concealed by a small tree(7)??T?OLE
12 down- Concerning "the ordinary keelie's swarm? Shove it!(10,three words) ?N????UI??
21 down-Black hankie's about a shivery spell?(6)??UM??