Actress Seydoux (3)
I believe the answer is:
lea
'actress seydoux' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for lea that I've seen before include "Meadow (poetic)" , "Tract of pastureland" , "authority for teachers" , "River of east London" , "Open area of grassy or arable land" .)