A court drama, in part (3)
I believe the answer is:
act
'drama in part' is the definition.
(act in a play)
'a court' is the wordplay.
'court' becomes 'ct'.
'a'+'ct'='ACT'
(Other definitions for act that I've seen before include "A deed or statute" , "work" , "Assumed attitude" , "Major section of a play" , "Do something (on stage?)" .)