Light tan (4)
'light tan' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ecru that I've seen before include "Buff or beige" , "Strange cure for a colour" , "Stange cure for a colour" , "light beige" , "Very light brown colour" .)
(Other definitions for beige that I've seen before include "Light sandy fawn colour" , "Taupe" , "Pale brown" , "Light brown" , "Fawn-coloured" .)