### Clue: Ancient city originally associated by students with a mythological god (6)
### Answer: URANUS 
 ### Explanation: Definition: a mythological god
 UR(city in Sumeria in ancient Mesopotamia) + **1st letter of**(originally) "associated" **plus**(by) NUS(abbrev. for the National Union of Students in the UK).
Defn: … personifying the sky.