Celebrity takes directors to one side (9)
I believe the answer is:
starboard
'one side' is the definition.
(I know that starboard is a type of side)
'celebrity takes directors' is the wordplay.
'celebrity' becomes 'star' (a star is a celebrity or famous person).
'takes' says to put letters next to each other.
'directors' becomes 'board' (board of directors).
'star'+'board'='STARBOARD'
'to' is the link.
(Other definitions for starboard that I've seen before include "Sailor's right" , "Right side of ship or plane" , "Right side at sea" , "One side of a ship" , "right to 14 [YACHTS]" .)