How does Clifton employ symbolism and imagery in her poem "There Is a Girl Inside"?
Imagery is when the poet uses language meant to convey sensory information; so it can be visual (seeing), auditory (hearing), tactile (touch), gustatory (taste), or olfactory (smell). The image of "a green tree in a forest of kindling" is a very clear visual image, as is the image of the speaker "break[ing] through gray hairs / into blossom."
The "girl inside" is actually a metaphor for the way the speaker, presumably a woman of advanced years, feels inside: she does not feel like an old woman on the inside. We can identify it as a metaphor and not a symbol, proper, because the speaker does not literally have a girl inside her (and a symbol must work both literally and figuratively). Instead, she feels like a young woman, a woman who is "randy as a wolf," which is a simile used to convey the continuation of the speaker's sexual desire. She is a "green tree in a forest of kindling," which is a metaphor used to show the way her youthful insides seem to be surrounded by her aged exterior. Another simile in the quote "she has waited patient as a nun" is used to convey the speaker's faithful expectation that she will, someday, become or at least be recognized as young again. Also, the contrast between calling the girl "randy" but then comparing her to a nun is strange and unsettling, which leads up to the final image of "lovers . . . harvest[ing] / honey and thyme," presumably from this metaphorical tree. However, the words seem sexual here again, too, as if the woods will go wild as a result of the wonder that this older woman still has such passion to be "harvest[ed]," which is another metaphor.
Imagery is the use of words to create a mental picture--which Lucille Clifton was very good at doing.
This poem is about growing old in body but not in spirit. Clifton says there is a young girl inside her who "will not walk away/ and leave these bones/ to an old woman." She will not let the condition of her body make her mind and spirit old.
Clifton uses the image of a green tree in a "forest of kindling," meaning dried-out wood ready for burning, to symbolize the young spirit, the "green girl," inside her.
She uses the image of a nun waiting patiently for the second coming to symbolize her patience in waiting for that day, presumably after death, when she will have the new body promised to believers (I realize I'm reading a lot into this). She returns to the image of the green tree to symbolize that new, young body.
She turns from religious imagery to recall the metaphor of being "randy as a wolf" (meaning she's in "heat") from the first stanza. The wild growth of the woods after her lovers have "harvested" her "honey and thyme" symbolizes the sexual potency and fertility of her new body.