Battle colour (7)
I believe the answer is:
magenta
This clue is a double definition.
'battle' is the first definition.
(Magenta is an example)
'colour' is the second definition.
(magenta is a kind of colour)
(Other definitions for magenta that I've seen before include "Deep purplish red" , "Reddish purple" , "Colourful" , "Purplish-red - battle" , "Bright purplish-red" .)