A lark is a small brown bird which sings as it flies. You have to look up to see them, but not neccesarily early in the morning.
Larking around is behaving in a playful or mischevious way. A lark can be something done for fun, but is often considered silly or a waste of time. As a lark, a former colleague made me this map.
There's nothing playful or silly about this competition. There is a top prize of £200 though and you can enter a fiction or poetry.
UPDATE - Here's a competition for novel openings, but you need to be quick.