Heading for Appeal Court to take the initiative (3)
I believe the answer is:
act
'take the initiative' is the definition.
(I've seen this in another clue)
'heading for appeal court to' is the wordplay.
'heading for' suggests taking the first letters.
The initial letters of 'appeal court to' is 'ACT'.
(Other definitions for act that I've seen before include "Take part in a play" , "Routine" , "Perform - part of a play" , "Behave like thespian" , "Major section of a play" .)