Ostentatious jewellery (5)
I believe the answer is:
'ostentatious jewellery' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for bling that I've seen before include "Flashy, ostentatious jewellery" , "Jewellery for show" , "Jazzy" , "Showy jewellery" , "Showy jewels etc" .)