Model of a flag? (8)
I believe the answer is:
standard
This clue is a double definition.
'model' is the first definition.
(I've seen this before)
'a flag?' is the second definition.
(standard is a kind of flag)
'of' is the link.
(Other definitions for standard that I've seen before include "Flag - pattern - guide" , "Conventional" , "Principle" , "Typical, normal" , "authority" .)