Ostentatious (5)
I believe the answer is:
showy
'ostentatious' is the definition.
(similar in meaning)
This is all the clue.
(Other definitions for showy that I've seen before include "Strikingly colourful" , "Strikingly bright" , "Colourful, ostentatious" , "Ostentatious, bright" , "Flamboyant" .)