Playwright’s aphorism enthralling hearts (4)
I believe the answer is:
shaw
'playwright's' is the definition.
(George Bernard Shaw)
'aphorism enthralling hearts' is the wordplay.
'aphorism' becomes 'saw' (I've seen this in another clue).
'enthralling' indicates putting letters inside.
'hearts' becomes 'h' (abbreviation used in card games e.g. bridge).
'saw' placed around 'h' is 'SHAW'.
(Other definitions for shaw that I've seen before include "Irish playwright, d. 1950" , "G. B. ---; T. E. ---" , "Major Barbara playwright" , "George Bernard -, Irish dramatist" , "Man and Superman playwright" .)