No. 4.

I am composed of 21 letters, and am the title of a poem by Bret Harte.

My 7, 19, 4 does not mean to sail.

My 15, 20, 6, 14, 3 will always prevail.

My 11, 10, 12 obscures the sight.

My 9, 6, 8 is an orb of light.

My 1, 2, 16 is caused by pleasure.

My 7, 13, 17, 14 is a time of leisure.

My 5, 6, 18 is the nickname of a boy.

My 9, 2, 4, 21 sometimes expresses joy.

Harry Thorne.