Bearded lefty regularly snug in slippers? (6)
I believe the answer is:
engels
'bearded lefty' is the definition.
The definition suggests a singular noun which matches the answer.
'regularly snug in slippers?' is the wordplay.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
'in' means one lot of letters goes inside another.
'slippers?' becomes 'eels' (I can't justify this - if you can you should give a lot more credence to this answer).
The alternating letters of 'snug' are 'ng'.
'ng' placed into 'eels' is 'ENGELS'.
Can you help me to learn more?
(Other definitions for engels that I've seen before include "German philosopher and collaborator of Marx" , "Friedrich --, associate of Karl Marx" , "Co-author of Karl Marx" , "Communism founder" , ". . . and his friend, Friedrich" .)