The best governing body is right! (9)
I believe the answer is:
starboard
'is right' is the definition.
(right side of a ship)
'the best governing body' is the wordplay.
'the best' becomes 'star' (star can mean the best or most excellent).
'governing body' becomes 'board' (I've seen this in another clue).
'star'+'board'='STARBOARD'
(Other definitions for starboard that I've seen before include "Opposite of port" , "Right side of ship or plane" , "right to 14 [YACHTS]" , "Sailor's right" , "Literally, the steering side of a vessel" .)