Titled lady enthralled by high-powered American (4)
I believe the answer is:
dame
'titled lady' is the definition.
(I've seen this before)
'enthralled by high-powered american' is the wordplay.
'enthralled by' indicates a hidden word.
'DAME' is hidden in the letters of 'high powered american'.
(Other definitions for dame that I've seen before include "British title for a lady" , "Pantomime character" , "Lady's title" , "Pantomime female" , "Titled lady" .)