Be back in time for discussion (6)
I believe the answer is:
debate
'for discussion' is the definition.
(debate is a kind of discussion)
'be back in time' is the wordplay.
'back' says the letters should be written in reverse.
'in' means one lot of letters goes inside another.
'time' becomes 'date' (date is a kind of time).
'be' backwards is 'eb'.
'eb' inserted within 'date' is 'DEBATE'.
(Other definitions for debate that I've seen before include "Exchange of views" , "Verbal disputation" , "Argue the toss" , "Public discussion, perhaps a contest" , "Discuss through argument" .)