### Clue: Erratic leader of London embroiled in capital cock-up (7)
### Answer: AIMLESS 
 ### Explanation: Definition: Erratic
 **The 1st letter of**(leader of) "London " **contained in**(embroiled in) [AI(with the Roman numeral, A1;excellent;capital!) + MESS(a cock-up;a balls-up).