Clue: US poet starts to open up, led by divine spirit (7)
Answer: ANGELOU
Explanation: Definition: US poet
[*starts to*] **O**(pen) **U**(p), *led by* **ANGEL** ("divine spirit") 
*Refers to Maya Angelou, the US poet whose authobiographies, including *I Know Why the Caged Bird Sings*, are more well-known than her poetry.