Ancient city - sacred tours every 60 minutes (6)
I believe the answer is:
hourly
'every 60 minutes' is the definition.
(I've seen this in another clue)
'ancient city sacred tours' is the wordplay.
'ancient city' becomes 'ur' (ancient Sumerian city state).
'sacred' becomes 'holy' (similar in meaning).
'tours' is an insertion indicator (to tour can mean to go around).
'ur' going into 'holy' is 'HOURLY'.
(Other definitions for hourly that I've seen before include "Every 60 minutes" , "Every sixty minutes" , "Every 3,600 seconds" .)