American TV agenda ruined profit (9)
I believe the answer is:
advantage
'profit' is the definition.
(I've seen this before)
'american tv agenda ruined' is the wordplay.
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'ruined' is an anagram indicator.
'tv'+'agenda'='tvagenda'
'tvagenda' is an anagram of 'dvantage'.
'a'+'dvantage'='ADVANTAGE'
(Other definitions for advantage that I've seen before include "Superior or more favourable position" , "Favourable circumstance" , "Profit, tennis score" , "Edge, head start" , "Asset" .)