New revolutionary has hard question (4)
I believe the answer is:
when
'question' is the definition.
(when is a question word)
'new revolutionary has hard' is the wordplay.
'revolutionary' says the letters should be written backwards (letters revolve around).
'has' indicates putting letters inside.
'hard' becomes 'h' (abbreviation used in pencil classifications).
'new' back-to-front is 'wen'.
'wen' enclosing 'h' is 'WHEN'.
(Other definitions for when that I've seen before include "At what time?" , "Say it when you''ve had enough" , "Over what period?" , "stop pouring the drink" , "As soon as" .)