Bluish-purple colour (6)
I believe the answer is:
violet
'bluish-purple colour' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for violet that I've seen before include "Bluish purple" , "Five-petalled flower" , "Herbaceous flower" , "It nods on Oberon's bank" , "Colour at opposite end of spectrum from red" .)