Marxist compiler is a bounder (3,6)
I believe the answer is:
red setter
'a bounder' is the definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.
'marxist compiler' is the wordplay.
'marxist' becomes 'red' (red can mean a revolutionary).
'compiler' becomes 'setter' (both can mean a writer of crosswords).
'red'+'setter'='RED SETTER'
'is' is the link.
Can you help me to learn more?
(Other definitions for red setter that I've seen before include "description of evening sun?" , "My best friend" , "supplier of crosswords to the Daily Worker?" , "Breed of dog" , "Gun dog" .)