Nothing that’s revolutionary in revolution? (4)
I believe the answer is:
love
'nothing' is the definition.
(I've seen this before)
'revolutionary in revolution?' is the wordplay.
'revolutionary' is a reversal indicator.
'in' indicates a hidden word.
'evol' is hidden in the letters of 'revolution'.
'evol' backwards is 'LOVE'.
'that's' is the link.
(Other definitions for love that I've seen before include "See 22" , "Precious" , "Intense affection" , "Zero score, dear" , ""Tell me the truth about ___" (Auden)" .)