Melodramatic hit act with Lear going mad (10)
I believe the answer is:
theatrical
'melodramatic' is the definition.
('theatrical' can be similar in meaning to 'melodramatic')
'hit act with lear going mad' is the wordplay.
'with' is a charade indicator (letters next to each other).
'going mad' is an anagram indicator.
'hit'+'act'+'lear'='hitactlear'
'hitactlear' is an anagram of 'THEATRICAL'.
(Other definitions for theatrical that I've seen before include "Stagy" , "Relating to acting/actors" , "Artificial and exaggerated" , "overdramatic" , "Showbiz" .)