### Clue: Bismuth has to turn red, perhaps piebald (8)
### Answer: BICOLOUR 
 ### Explanation: Definition: perhaps piebald
 BI(symbol for the chemical element, bismuth) **plus**(has) COLOUR(to turn red, said of a person or person's skin blushing with embarrassment or shame).
Defn: An example/perhaps is "piebald", descriptive of an animal, especially a horse, with a patchy coat of 2 colours.  It is also descriptive of some minerals.