Drivers touring ancient city creating atmosphere (4)
I believe the answer is:
aura
'atmosphere' is the definition.
(synonyms)
'drivers touring ancient city' is the wordplay.
'drivers' becomes 'AA' (Automobile Association).
'touring' indicates putting letters inside (touring can mean going round).
'ancient city' becomes 'ur' (ancient Sumerian city state).
'aa' going around 'ur' is 'AURA'.
'creating' is the link.
(Other definitions for aura that I've seen before include "Glorious glow" , "Distinctive atmosphere surrounding person or thing" , "Distinctive character, essence of a living thing" , "Supposed emanation surrounding the body" , "Air, distinctive character" .)