Be back in appointed time for discussion (6)
I believe the answer is:
debate
'discussion' is the definition.
(debate is a kind of discussion)
'be back in appointed time' is the wordplay.
'back' says the letters should be written backwards.
'in' means one lot of letters goes inside another.
'appointed time' becomes 'date' (date is a kind of time. I am not sure about the 'appointed' bit.).
'be' backwards is 'eb'.
'eb' placed within 'date' is 'DEBATE'.
'for' is the link.
Can you help me to learn more?
(Other definitions for debate that I've seen before include "Discussion with arguments for and against" , "Talk" , "Argue a point" , "Public discussion, perhaps a contest" , "Exchange of views" .)