Enthusiast takes a friend to ancient city (7)
I believe the answer is:
amateur
'enthusiast' is the definition.
(thesaurus)
'a friend to ancient city' is the wordplay.
'friend' becomes 'mate' (mate is a kind of friend).
'to ancient city' becomes 'ur'.
'a'+'mate'+'ur'='AMATEUR'
'takes' acts as a link.
(Other definitions for amateur that I've seen before include "unskilful" , "Dabbler" , "lacking professional expertise" , "enthusiast" , "He's not professional" .)