Revolutionary coming back to eat pub grub? (6)
I believe the answer is:
dinner
'grub?' is the definition.
(I've seen this before)
'revolutionary coming back to eat pub' is the wordplay.
'revolutionary' becomes 'red'.
'coming back' shows that the letters should be reversed in order.
'to eat' means one lot of letters goes inside another.
'pub' becomes 'inn' (I've seen this before).
'red' back-to-front is 'der'.
'der' going around 'inn' is 'DINNER'.
(Other definitions for dinner that I've seen before include "serving in 20 [MESS] ?" , "What feeds" , "Repast" , "Supper" , "Eat it in the strange red inn" .)