Colour has a brand (5)
I believe the answer is:
taint
'brand' is the definition.
(thesaurus)
'colour has a' is the wordplay.
'colour' becomes 'tint' (tint is a kind of colour).
'has' is an insertion indicator.
'tint' placed around 'a' is 'TAINT'.
(Other definitions for taint that I've seen before include "It isn't commonly" , "Adulterate" , "Contaminate, pollute" , "Contaminating influence" , "contaminant" .)