Socialist cleaner may flag (3,6)
I believe the answer is:
'flag' is the definition.
Both the definition and answer are singular nouns.
Perhaps there's an association between them I don't understand?
'socialist cleaner' is the wordplay.
'socialist' becomes 'red' (socialism is often associated with the colour red).
'cleaner' becomes 'duster' (dusting is a type of cleaning).
'may' is the link.
Can you help me to learn more?
(Other definitions for red duster that I've seen before include "British merchant navy flag" , "Signal" , "Ensign" .)