Lacking pigmentation (6)
I believe the answer is:
albino
'lacking pigmentation' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for albino that I've seen before include "Animal with pigment deficiency" , "A plant lacking in pigment" , "One devoid of natural pigmentation" , "Animal or plant lacking pigmentation" , "Person lacking pigment" .)