Between black and white (4)
I believe the answer is:
grey
'between black and white' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for grey that I've seen before include "Colour (of fifty shades?)" , "The colour of ash" , "11 - if of 10, white" , "Colour of lead" , "Lady Jane --" .)