Dramatic princess entertaining American president (6)
I believe the answer is:
reagan
'american president' is the definition.
(I've seen this before)
'dramatic princess entertaining' is the wordplay.
'dramatic' becomes 'a' (I can't explain this - if you can you should give a lot more credence to this answer).
'princess' becomes 'regan' (character in King Lear).
'entertaining' indicates putting letters inside.
'a' put inside 'regan' is 'REAGAN'.
Can you help me to learn more?
(Other definitions for reagan that I've seen before include "Former US president" , "Ronald . . . . . ., a film star and president" , "40th US president, Ronald" , "Former leader" , "US president lived in a strange RNA age" .)