This setter's a brute oddly lacking colour (5)
I believe the answer is:
imbue
'colour' is the definition.
(I know this)
'this setter's a brute oddly lacking' is the wordplay.
'this setter's' becomes 'Im' (referring to the person who set the crossword).
'oddly lacking' indicates alternate letters (letters in odd-numbered positions removed).
The alternate letters of 'brute' are 'bue'.
'im'+'bue'='IMBUE'
(Other definitions for imbue that I've seen before include "Permeate - inspire" , "Fill, with colour or feeling" , "Penetrate" , "dye" , "Inspire (with ideals)" .)