Chap finds ancient city ruin (7)
I believe the answer is:
destroy
'ruin' is the definition.
('destroy' can be a synonym of 'ruin')
'chap finds ancient city' is the wordplay.
'chap' becomes 'des' (**).
'finds' is a charade indicator (letters next to each other).
'ancient city' becomes 'troy' (I've seen this before).
'des'+'troy'='DESTROY'
(Other definitions for destroy that I've seen before include "Kill; ruin" , "Obliterate" , "put to death" , "Ruin; pull down" , "Demolish; pull down" .)