Flag to be situated above a road (8)
I believe the answer is:
standard
'flag' is the definition.
(I know that standard is a type of flag)
'situated above a road' is the wordplay.
'situated above' becomes 'stand' (I am not sure about this - if you are sure you should believe this answer much more).
'road' becomes 'rd' (abbreviation).
'stand'+'a'+'rd'='STANDARD'
'to be' is the link.
Can you help me to learn more?
(Other definitions for standard that I've seen before include "Established or accepted model" , "Criterion, touchstone" , "Flag - level of attainment" , "Flag - of the usual kind" , "Possible 1930s song" .)