A friend finds ancient city crude (7)
I believe the answer is:
amateur
'crude' is the definition.
(thesaurus)
'a friend finds ancient city' is the wordplay.
'friend' becomes 'mate' (mate is a kind of friend).
'finds' means one lot of letters go next to another.
'ancient city' becomes 'ur' (ancient Sumerian city state).
'a'+'mate'+'ur'='AMATEUR'
(Other definitions for amateur that I've seen before include "He's not professional" , "Lover" , "hobbyist" , "lacking professionalism" , "Person who does something as a pastime rather than a profession" .)