Colourful battle (7)
I believe the answer is:
magenta
I believe this clue is a double definition.
'colourful' is the first definition.
(I've seen this before)
'battle' is the second definition.
(Magenta is an example)
(Other definitions for magenta that I've seen before include "Colour named after a bloody 1859 battle in Italy" , "Name tag (anag) - colour" , "French victory" , "A crimson dye" , "Shade of purple" .)