How does Clarke bring out the theme of teaching in the poem "Clocks"? Support your answer with the help of poetic devices.

In this poem, the narrator is teaching a young boy while taking a walk with him. She picks a dandelion and uses it to begin teaching him to tell time:

I teach him to tell the timeby dandelion. "One o'clock. Two."

In treating the dandelion as if it is a clock, she is using metaphor, which is likening one thing to another without using the words "like" or "as." She sees that the dandelion is round like the face of the clock, so she can use it to start showing him the location of the numbers on a clock.
He doesn't show much interest in learning to tell time, for he blows "a field of gold from the palm of his hand," presumably the petals she has plucked from the dandelion and placed in his palm as she is teaching him about time. Here, the narrator uses the literary device of imagery to show how the child blows away (blows off) her interest in teaching him what she wants him to know. What he learns, she says, is the "power of naming."
In the next stanza, the narrator and the child are walking along the beach at sunset. Clarke uses the literary device of alliteration to emphasize the child's nervousness at being by the sea. Alliteration is when words placed close together begin with the same letter. Here we learn he is "wary of waves and sand's soft treachery." The repeated "w" and "s" sounds draw attention to words that connote his sense of his worry in this new place.
The narrator continues to try to teach him, this time by asking a question that perhaps is meant to make him feel more comfortable about the crashing of the waves:

What does the sea say?

This is a fanciful inquiry that uses the literary device of personification to teach. Personification is treating an animal or object that is not human as if it is a human by giving it human characteristics. Here, the narrator is acting as if they sea can talk to us as if it is a person. The boy responds as follows:

"Ffwff! Ffwff!" he answers, then turnshis face to the sky and points to the full-blown moon.

"Ffwff" is his word for flower. He says the waves are naming the moon a flower. He demonstrates he has learned the "power of naming." He has also, although without realizing it, learned to use metaphor; after all, the moon is not a flower, but it is round, beautiful, and blooming like a flower.
The poem also uses the literary device of enjambment to emphasize the theme of teaching. Enjambment is when a line a poetry doesn't end at the end of a line but flows into the next line, such as in

I teach him to tell the timeby dandelion

There's a pause and sense of surprise in breaking the line at the word "time" and finishing it with the idea of "by dandelion," which mirrors some of the surprise that comes with teaching and learning.
Clarke thus uses the literary devices of metaphor, imagery, alliteration, personification, and enjambment to highlight the theme of teaching. The poem shows the child learning what he wants to learn and learning through making connections between one thing and another, such as a dandelion and the moon.