Prize public house within ancient city (6)
I believe the answer is:
trophy
'prize' is the definition.
(synonyms)
'public house within ancient city' is the wordplay.
'public house' becomes 'ph'.
'within' means one lot of letters goes inside another.
'ancient city' becomes 'troy' (I've seen this before).
'ph' inserted within 'troy' is 'TROPHY'.
(Other definitions for trophy that I've seen before include "Laurels" , "Prize symbolising victory" , "Prize or token of victory" , "Award cup" , "Prize, eg cup" .)