One of twelve in court (5)
I believe the answer is:
juror
'one of twelve in court' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for juror that I've seen before include "person to deliver verdict" , "One of 12 in court" , "One of those responsible for verdict" , "Trial panellist" , "One empanelled in court" .)