Marxist lark, possibly? (4)
I believe the answer is:
karl
'marxist' is the definition.
Both the definition and answer are singular nouns.
Perhaps you can see an association between them that I can't see?
'lark possibly?' is the wordplay.
'possibly?' is an anagram indicator (I've seen 'possibly' mean this).
'lark' is an anagram of 'KARL'.
Can you help me to learn more?
(Other definitions for karl that I've seen before include "Founder of communism, . . . . Heinrich Marx" , "-- Marx, socialist" .)