Conspirator's heart displayed in conspiracy trial (5)
I believe the answer is:
pilot
'trial' is the definition.
(I've seen this before)
'conspirator's heart displayed in conspiracy' is the wordplay.
'heart' means to look at the middle letters.
'displayed in' indicates putting letters inside.
'conspiracy' becomes 'plot' (I've seen this before).
The middle letter of 'conspirator' is 'i'.
'i' going inside 'plot' is 'PILOT'.
(Other definitions for pilot that I've seen before include "Navigate" , "Ship's guide" , "Plane flyer" , "One-off programme" , "Person in charge of aircraft" .)