### Clue: Greek poet's energy about to inspire one of her letters (7)
### Answer: SAPPHIC 
 ### Explanation: Definition: Greek poet's
 [ SAP(energy;vigour) + C(abbrev. for "circa";about, in relation to dates and periods) ] **containing**(to inspire) PHI(a letter in the Greek alphabet).
Answer: Relating to;of;…'s Sappho, Archaic Greek poetess from the island **
of Lesbos.