Clue: In America, unfairly, Hillary's No 1 female monster (8)
Answer: CHIMAERA
Explanation: Definition: female monster
An envelope ('in') of H ('**H**illary's No 1′) in CIMAERA, an anagram ('unfairly') of 'America'. In Greek mythology, the Chimaera was a fire-breathing she-monster with a lion's head, a goat's body, and a serpent's tail (or some such hybrid). The surface has a more contemporary ring to it.