In Country Sleep
by Dylan Thomas
Never and never, my girl riding far and near
In the land of the hearthstone tales, and spelled asleep,
Fear or believe that the wolf in a sheepwhite hood
Loping and bleating roughly and blithely shall leap, My dear, my dear,
Out of a lair in the flocked leaves in the dew dipped year
To eat your heart in the rosy wood.
spell= a spell cast by someone, like a witch Generally, we say to cast a spell; Here Thomas makes it a verb to mean she has been put to sleep with a spell.
Basically, Thomas is saying: If you (my girl) are riding your horse out in the country or near home (hearthstone tales suggests stories told by the hearth, in cottages, i.e. in the country) and are asleep (i.e. dreaming) never believe a wolf in sheep's clothing (which is a well-known saying in English, which he re-invents) will come out of its lair sounding like a sheep (sheep bleat) and without a second thought (blithely) to eat your heart in the woods.
Notice: Generally, we say flocks of sheep. Here, the genius is to apply flocking i.e. grouping together, to the leaves rather than sheep, to avoid a cliché.
dew dipped year = Sheep are dipped in some chemical bath or other to protect them against various things. It's is known as "sheep dip".
Here, the poet takes the the idea of dipping and applies it to dew, generally considered a gentle thing; the water that appears on grass and plants in the morning.
So, dew dipped year can be a gentle or nice year, all around. Maybe there are other readings here. That's mine.
Finally, rosy wood suggest a wood (small forest) covered with a mushroom called rosy wood or the wood in the morning with just a little sun that makes it look pink.
The overall structure of the poem is in the imperative: Never fear or believe [etc. etc]
Never, never my girl [when you are] riding far and near fear or believe that X (dependent clause) will leap out TO [purpose].
That's basically it.