The very best directors are right (9)
I believe the answer is:
starboard
'are right' is the definition.
(right side of a ship)
'the very best directors' is the wordplay.
'the very best' becomes 'star' (star can mean the best or most excellent. I am not sure about the 'very' bit.).
'directors' becomes 'board' (board of directors).
'star'+'board'='STARBOARD'
Can you help me to learn more?
(Other definitions for starboard that I've seen before include "Opposite of port" , "Right side at sea" , "Literally, the steering side of a vessel" , "Right-hand side of ship while facing forward" , "One side of a ship" .)