Heraldic device (6)
I believe the answer is:
emblem
'heraldic device' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for emblem that I've seen before include "Device, badge or symbol" , "Symbol; heraldic device" , "Symbol, device that represents something" , "Symbolic device or badge" , "Symbolic object" .)