Child going round ancient city is a sightseer (7)
I believe the answer is:
tourist
'a sightseer' is the definition.
(someone visiting certain sights)
'child going round ancient city is' is the wordplay.
'child' becomes 'tot' (term for a young child).
'going round' means one lot of letters goes inside another (some letters go around others).
'ancient city' becomes 'ur' (ancient Sumerian city state).
'ur'+'is'='uris'
'tot' going around 'uris' is 'TOURIST'.
(Other definitions for tourist that I've seen before include "One travels for pleasure" , "Cheap travel class" , "Person travelling for pleasure" , "Someone who travels for pleasure" , "Tripper, sightseer" .)