Hair highlight (6)
I believe the answer is:
streak
'hair highlight' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for streak that I've seen before include "Band of colour - run naked" , "Run naked in a public place" , "Go faster" , "act that may offend some spectators?" , "Run naughtily nude in public" .)