Those engaged in supporting the flag? (5)
I believe the answer is:
staff
'flag?' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Perhaps there's a link between them I don't understand?
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for staff that I've seen before include "Rules needed for scoring" , "Personnel or wooden pole" , "Stick - office employees" , "support for notes" , "five lines?" .)