Full range of colour (8)
I believe the answer is:
spectrum
'full range of colour' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for spectrum that I've seen before include "Full range of colour" , "range of tones" , "Broad range of related items" , "A broad range, of colours say" , "Bands of colour in crumpets" .)