Master a mad role, performing in sensational play (9)
I believe the answer is:
melodrama
'sensational play' is the definition.
(I've seen this before)
'master a mad role performing' is the wordplay.
'master' becomes 'm'.
'performing' indicates an anagram.
'a'+'mad'+'role'='amadrole'
'amadrole' is an anagram of 'elodrama'.
'm'+'elodrama'='MELODRAMA'
'in' is the link.
(Other definitions for melodrama that I've seen before include "Sensational type of play" , "sensational affair" , "Histrionics - sensational play" , "Over-sensational play" , "sensational performance" .)